Bump rack-attack from 6.3.0 to 6.3.1 (#13849)

Bumps [rack-attack](https://github.com/kickstarter/rack-attack) from 6.3.0 to 6.3.1.
- [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/v6.3.0...v6.3.1)

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

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

Gemfile.lock

@@ -439,7 +439,7 @@ GEM
       activesupport (>= 3.0.0)
     raabro (1.3.1)
     rack (2.2.2)
-    rack-attack (6.3.0)
+    rack-attack (6.3.1)
       rack (>= 1.0, < 3)
     rack-cors (1.1.1)
       rack (>= 2.0.0)