Bump rubocop-rspec from 2.16.0 to 2.18.0 (mastodon#23122)

Bumps [rubocop-rspec](https://github.com/rubocop/rubocop-rspec) from 2.16.0 to 2.18.0.
- [Release notes](https://github.com/rubocop/rubocop-rspec/releases)
- [Changelog](https://github.com/rubocop/rubocop-rspec/blob/master/CHANGELOG.md)
- [Commits](rubocop/rubocop-rspec@v2.16.0...v2.18.0)

---
updated-dependencies:
- dependency-name: rubocop-rspec
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

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

Gemfile.lock

@@ -596,15 +596,18 @@ GEM
       unicode-display_width (>= 2.4.0, < 3.0)
     rubocop-ast (1.24.1)
       parser (>= 3.1.1.0)
+    rubocop-capybara (2.17.0)
+      rubocop (~> 1.41)
     rubocop-performance (1.15.2)
       rubocop (>= 1.7.0, < 2.0)
       rubocop-ast (>= 0.4.0)
     rubocop-rails (2.17.4)
       activesupport (>= 4.2.0)
       rack (>= 1.1)
       rubocop (>= 1.33.0, < 2.0)
-    rubocop-rspec (2.16.0)
+    rubocop-rspec (2.18.0)
       rubocop (~> 1.33)
+      rubocop-capybara
     ruby-progressbar (1.11.0)
     ruby-saml (1.13.0)
       nokogiri (>= 1.10.5)