chore(deps): bump rubocop in /fluent-plugin-kubernetes-metadata-filter

Bumps [rubocop](https://github.com/rubocop/rubocop) from 1.12.0 to 1.12.1.
- [Release notes](https://github.com/rubocop/rubocop/releases)
- [Changelog](https://github.com/rubocop/rubocop/blob/master/CHANGELOG.md)
- [Commits](rubocop/rubocop@v1.12.0...v1.12.1)

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

fluent-plugin-kubernetes-metadata-filter/Gemfile.lock

@@ -101,7 +101,7 @@ GEM
     regexp_parser (2.1.1)
     rexml (3.2.4)
     rr (1.2.1)
-    rubocop (1.12.0)
+    rubocop (1.12.1)
       parallel (~> 1.10)
       parser (>= 3.0.0.0)
       rainbow (>= 2.2.2, < 4.0)