Bump syn from 1.0.15 to 1.0.16 (#907)

Bumps [syn](https://github.com/dtolnay/syn) from 1.0.15 to 1.0.16.
- [Release notes](https://github.com/dtolnay/syn/releases)
- [Commits](https://github.com/dtolnay/syn/compare/1.0.15...1.0.16)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

Cargo.lock

@@ -370,9 +370,9 @@ checksum = "5c2fb2ec9bcd216a5b0d0ccf31ab17b5ed1d627960edff65bbe95d3ce221cefc"
 
 [[package]]
 name = "syn"
-version = "1.0.15"
+version = "1.0.16"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7a0294dc449adc58bb6592fff1a23d3e5e6e235afc6a0ffca2657d19e7bbffe5"
+checksum = "123bd9499cfb380418d509322d7a6d52e5315f064fe4b3ad18a53d6b92c07859"
 dependencies = [
  "proc-macro2",
  "quote",