chore(ci): Make dependabot track github actions

Author: abusch

.github/dependabot.yml

@@ -12,3 +12,9 @@ updates:
     ignore:
       - dependency-name: "*"
         update-types: ["version-update:semver-patch"]
+  # Make sure github actions like release-plz stay up to date
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    # Check for updates every Monday
+    schedule:
+      interval: "weekly"