Bump racc from 1.7.2 to 1.7.3

Bumps [racc](https://github.com/tenderlove/racc) from 1.7.2 to 1.7.3.
- [Release notes](https://github.com/tenderlove/racc/releases)
- [Changelog](https://github.com/ruby/racc/blob/master/ChangeLog)
- [Commits](ruby/racc@v1.7.2...v1.7.3)

---
updated-dependencies:
- dependency-name: racc
  dependency-type: indirect
  update-type: version-update:semver-patch
...

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

gems.locked

@@ -74,7 +74,7 @@ GEM
     parser (3.2.2.4)
       ast (~> 2.4.1)
       racc
-    racc (1.7.2)
+    racc (1.7.3)
     rainbow (3.1.1)
     rake (13.1.0)
     regexp_parser (2.8.2)