Update dependency rack-attack to v6.8.0

Author: renovate[bot]

Gemfile.lock

@@ -272,8 +272,8 @@ GEM
     puma (7.0.4)
       nio4r (~> 2.0)
     racc (1.8.1)
-    rack (3.1.17)
-    rack-attack (6.7.0)
+    rack (3.1.18)
+    rack-attack (6.8.0)
       rack (>= 1.0, < 4)
     rack-session (2.1.1)
       base64 (>= 0.1.0)