Bump racc from 1.7.3 to 1.8.1

Bumps [racc](https://github.com/ruby/racc) from 1.7.3 to 1.8.1.
- [Release notes](https://github.com/ruby/racc/releases)
- [Changelog](https://github.com/ruby/racc/blob/master/ChangeLog)
- [Commits](ruby/racc@v1.7.3...v1.8.1)

---
updated-dependencies:
- dependency-name: racc
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Gemfile.lock

@@ -17,7 +17,7 @@ GEM
     parser (3.3.0.4)
       ast (~> 2.4.1)
       racc
-    racc (1.7.3)
+    racc (1.8.1)
     rainbow (3.1.1)
     rake (13.1.0)
     rake-compiler (1.2.5)