chore(deps): bump proc-macro2 from 1.0.38 to 1.0.39 (gakonst#1275)

Bumps [proc-macro2](https://github.com/dtolnay/proc-macro2) from 1.0.38 to 1.0.39.
- [Release notes](https://github.com/dtolnay/proc-macro2/releases)
- [Commits](dtolnay/proc-macro2@1.0.38...1.0.39)

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

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

ethers-core/Cargo.toml

@@ -39,7 +39,7 @@ cargo_metadata = { version = "0.14.2", optional = true }
 # eip712 feature enabled dependencies
 convert_case = { version = "0.5.0", optional = true }
 syn = { version = "1.0.94", optional = true }
-proc-macro2 = { version = "1.0.38", optional = true }
+proc-macro2 = { version = "1.0.39", optional = true }
 
 [dev-dependencies]
 serde_json = { version = "1.0.64", default-features = false }