Bump proc-macro2 from 1.0.59 to 1.0.60 (#498)

Bumps [proc-macro2](https://github.com/dtolnay/proc-macro2) from 1.0.59 to 1.0.60.
- [Release notes](https://github.com/dtolnay/proc-macro2/releases)
- [Commits](https://github.com/dtolnay/proc-macro2/compare/1.0.59...1.0.60)

---
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>

Cargo.lock

@@ -1273,9 +1273,9 @@ dependencies = [
 
 [[package]]
 name = "proc-macro2"
-version = "1.0.59"
+version = "1.0.60"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6aeca18b86b413c660b781aa319e4e2648a3e6f9eadc9b47e9038e6fe9f3451b"
+checksum = "dec2b086b7a862cf4de201096214fa870344cf922b2b30c167badb3af3195406"
 dependencies = [
  "unicode-ident",
 ]