chore: Don't attempt to upgrade Rails via dependabot

Author: olleolleolle

.github/dependabot.yml

@@ -16,6 +16,7 @@ updates:
   - dependency-name: pg
     versions:
     - ">= 1.2.a, < 1.3"
+  - dependency-name: rails
   - dependency-name: stripe
     versions:
     - "> 4.18.1"