build: bump rspec-mocks from 3.9.0 to 3.9.1 in /Library/Homebrew

Bumps [rspec-mocks](https://github.com/rspec/rspec-mocks) from 3.9.0 to 3.9.1.
- [Release notes](https://github.com/rspec/rspec-mocks/releases)
- [Changelog](https://github.com/rspec/rspec-mocks/blob/master/Changelog.md)
- [Commits](https://github.com/rspec/rspec-mocks/compare/v3.9.0...v3.9.1

)

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

Library/Homebrew/Gemfile.lock

@@ -72,7 +72,7 @@ GEM
     rspec-its (1.3.0)
       rspec-core (>= 3.0.0)
       rspec-expectations (>= 3.0.0)
-    rspec-mocks (3.9.0)
+    rspec-mocks (3.9.1)
       diff-lcs (>= 1.2.0, < 2.0)
       rspec-support (~> 3.9.0)
     rspec-retry (0.6.2)