test_env: hardcode major go version in use (#23464)

hardcode the version of test_env we use in docker, so that we can use
different major versions of golang between versions of Gitea

---------

Co-authored-by: Lauris BH <lauris@nix.lv>

.drone.yml

@@ -44,7 +44,7 @@ steps:
     depends_on: [deps-frontend]
 
   - name: lint-backend
-    image: gitea/test_env:linux-amd64  # https://gitea.com/gitea/test-env
+    image: gitea/test_env:linux-1.20-amd64  # https://gitea.com/gitea/test-env
     pull: always
     commands:
       - make lint-backend
@@ -58,7 +58,7 @@ steps:
         path: /go
 
   - name: lint-backend-windows
-    image: gitea/test_env:linux-amd64  # https://gitea.com/gitea/test-env
+    image: gitea/test_env:linux-1.20-amd64  # https://gitea.com/gitea/test-env
     commands:
       - make golangci-lint-windows vet
     environment:
@@ -73,7 +73,7 @@ steps:
         path: /go
 
   - name: lint-backend-gogit
-    image: gitea/test_env:linux-amd64  # https://gitea.com/gitea/test-env
+    image: gitea/test_env:linux-1.20-amd64  # https://gitea.com/gitea/test-env
     commands:
       - make lint-backend
     environment:
@@ -234,13 +234,13 @@ steps:
         path: /go
 
   - name: prepare-test-env
-    image: gitea/test_env:linux-amd64  # https://gitea.com/gitea/test-env
+    image: gitea/test_env:linux-1.20-amd64  # https://gitea.com/gitea/test-env
     pull: always
     commands:
       - ./build/test-env-prepare.sh
 
   - name: build
-    image: gitea/test_env:linux-amd64  # https://gitea.com/gitea/test-env
+    image: gitea/test_env:linux-1.20-amd64  # https://gitea.com/gitea/test-env
     user: gitea
     commands:
       - ./build/test-env-check.sh
@@ -255,7 +255,7 @@ steps:
         path: /go
 
   - name: test-pgsql
-    image: gitea/test_env:linux-amd64  # https://gitea.com/gitea/test-env
+    image: gitea/test_env:linux-1.20-amd64  # https://gitea.com/gitea/test-env
     user: gitea
     commands:
       - timeout -s ABRT 50m make test-pgsql-migration test-pgsql
@@ -336,13 +336,13 @@ steps:
         path: /go
 
   - name: prepare-test-env
-    image: gitea/test_env:linux-amd64  # https://gitea.com/gitea/test-env
+    image: gitea/test_env:linux-1.20-amd64  # https://gitea.com/gitea/test-env
     pull: always
     commands:
       - ./build/test-env-prepare.sh
 
   - name: build
-    image: gitea/test_env:linux-amd64  # https://gitea.com/gitea/test-env
+    image: gitea/test_env:linux-1.20-amd64  # https://gitea.com/gitea/test-env
     user: gitea
     commands:
       - ./build/test-env-check.sh
@@ -357,7 +357,7 @@ steps:
         path: /go
 
   - name: unit-test
-    image: gitea/test_env:linux-amd64  # https://gitea.com/gitea/test-env
+    image: gitea/test_env:linux-1.20-amd64  # https://gitea.com/gitea/test-env
     user: gitea
     commands:
       - make unit-test-coverage test-check
@@ -373,7 +373,7 @@ steps:
         path: /go
 
   - name: unit-test-gogit
-    image: gitea/test_env:linux-amd64  # https://gitea.com/gitea/test-env
+    image: gitea/test_env:linux-1.20-amd64  # https://gitea.com/gitea/test-env
     user: gitea
     commands:
       - make unit-test-coverage test-check
@@ -389,7 +389,7 @@ steps:
         path: /go
 
   - name: test-mysql
-    image: gitea/test_env:linux-amd64  # https://gitea.com/gitea/test-env
+    image: gitea/test_env:linux-1.20-amd64  # https://gitea.com/gitea/test-env
     user: gitea
     commands:
       - make test-mysql-migration integration-test-coverage
@@ -490,13 +490,13 @@ steps:
         path: /go
 
   - name: prepare-test-env
-    image: gitea/test_env:linux-amd64  # https://gitea.com/gitea/test-env
+    image: gitea/test_env:linux-1.20-amd64  # https://gitea.com/gitea/test-env
     pull: always
     commands:
       - ./build/test-env-prepare.sh
 
   - name: build
-    image: gitea/test_env:linux-amd64  # https://gitea.com/gitea/test-env
+    image: gitea/test_env:linux-1.20-amd64  # https://gitea.com/gitea/test-env
     user: gitea
     commands:
       - ./build/test-env-check.sh
@@ -511,7 +511,7 @@ steps:
         path: /go
 
   - name: test-mysql8
-    image: gitea/test_env:linux-amd64  # https://gitea.com/gitea/test-env
+    image: gitea/test_env:linux-1.20-amd64  # https://gitea.com/gitea/test-env
     user: gitea
     commands:
       - timeout -s ABRT 50m make test-mysql8-migration test-mysql8
@@ -580,13 +580,13 @@ steps:
         path: /go
 
   - name: prepare-test-env
-    image: gitea/test_env:linux-amd64  # https://gitea.com/gitea/test-env
+    image: gitea/test_env:linux-1.20-amd64  # https://gitea.com/gitea/test-env
     pull: always
     commands:
       - ./build/test-env-prepare.sh
 
   - name: build
-    image: gitea/test_env:linux-amd64  # https://gitea.com/gitea/test-env
+    image: gitea/test_env:linux-1.20-amd64  # https://gitea.com/gitea/test-env
     user: gitea
     commands:
       - ./build/test-env-check.sh
@@ -601,7 +601,7 @@ steps:
         path: /go
 
   - name: test-mssql
-    image: gitea/test_env:linux-amd64  # https://gitea.com/gitea/test-env
+    image: gitea/test_env:linux-1.20-amd64  # https://gitea.com/gitea/test-env
     user: gitea
     commands:
       - make test-mssql-migration test-mssql
@@ -660,13 +660,13 @@ steps:
         path: /go
 
   - name: prepare-test-env
-    image: gitea/test_env:linux-arm64  # https://gitea.com/gitea/test-env
+    image: gitea/test_env:linux-1.20-arm64  # https://gitea.com/gitea/test-env
     pull: always
     commands:
       - ./build/test-env-prepare.sh
 
   - name: build
-    image: gitea/test_env:linux-arm64  # https://gitea.com/gitea/test-env
+    image: gitea/test_env:linux-1.20-arm64  # https://gitea.com/gitea/test-env
     user: gitea
     commands:
       - ./build/test-env-check.sh
@@ -681,7 +681,7 @@ steps:
         path: /go
 
   - name: test-sqlite
-    image: gitea/test_env:linux-arm64  # https://gitea.com/gitea/test-env
+    image: gitea/test_env:linux-1.20-arm64  # https://gitea.com/gitea/test-env
     user: gitea
     commands:
       - timeout -s ABRT 50m make test-sqlite-migration test-sqlite