Bump rack-attack from 5.4.1 to 5.4.2 (#9186)

Bumps [rack-attack](https://github.com/kickstarter/rack-attack) from 5.4.1 to 5.4.2.
- [Release notes](https://github.com/kickstarter/rack-attack/releases)
- [Changelog](https://github.com/kickstarter/rack-attack/blob/master/CHANGELOG.md)
- [Commits](https://github.com/kickstarter/rack-attack/compare/v5.4.1...v5.4.2)

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

Gemfile.lock

@@ -421,7 +421,7 @@ GEM
       activesupport (>= 3.0.0)
     raabro (1.1.6)
     rack (2.0.5)
-    rack-attack (5.4.1)
+    rack-attack (5.4.2)
       rack (>= 1.0, < 3)
     rack-cors (1.0.2)
     rack-protection (2.0.4)