Bump rubocop from 1.3.0 to 1.3.1 (#15212)

Bumps [rubocop](https://github.com/rubocop-hq/rubocop) from 1.3.0 to 1.3.1.
- [Release notes](https://github.com/rubocop-hq/rubocop/releases)
- [Changelog](https://github.com/rubocop-hq/rubocop/blob/master/CHANGELOG.md)
- [Commits](https://github.com/rubocop-hq/rubocop/compare/v1.3.0...v1.3.1)

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Gemfile.lock

@@ -532,7 +532,7 @@ GEM
     rspec-support (3.9.3)
     rspec_junit_formatter (0.4.1)
       rspec-core (>= 2, < 4, != 2.12.0)
-    rubocop (1.3.0)
+    rubocop (1.3.1)
       parallel (~> 1.10)
       parser (>= 2.7.1.5)
       rainbow (>= 2.2.2, < 4.0)