Bump proc-macro2 from 1.0.103 to 1.0.104

Bumps [proc-macro2](https://github.com/dtolnay/proc-macro2) from 1.0.103 to 1.0.104.
- [Release notes](https://github.com/dtolnay/proc-macro2/releases)
- [Commits](dtolnay/proc-macro2@1.0.103...1.0.104)

---
updated-dependencies:
- dependency-name: proc-macro2
  dependency-version: 1.0.104
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

Cargo.lock

@@ -16,7 +16,7 @@ never = []
 
 [dependencies]
 heck = "0.5.0"
-proc-macro2 = "1.0.103"
+proc-macro2 = "1.0.104"
 quote = "1.0.42"
 syn = { version = "2.0.111", features = ["full"] }