Bump parser from 3.3.7.2 to 3.3.7.3 in /steep

Bumps [parser](https://github.com/whitequark/parser) from 3.3.7.2 to 3.3.7.3.
- [Changelog](https://github.com/whitequark/parser/blob/master/CHANGELOG.md)
- [Commits](whitequark/parser@v3.3.7.2...v3.3.7.3)

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

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

steep/Gemfile.lock

@@ -34,7 +34,7 @@ GEM
     logger (1.6.6)
     minitest (5.25.5)
     mutex_m (0.3.0)
-    parser (3.3.7.2)
+    parser (3.3.7.3)
       ast (~> 2.4.1)
       racc
     racc (1.8.1)