Do not update patch versions for dependabot/github-actions. (#8946)

Towards flutter/flutter#158350.

Author: matanlurey

.github/dependabot.yml

@@ -10,3 +10,8 @@ updates:
     labels:
       - "autosubmit"
       - "release-notes-not-required"
+    # Updating patch versions for "github-actions" is too chatty.
+    # See https://github.com/flutter/flutter/issues/158350.
+    ignore:
+      - dependency-name: "*"
+        update-types: ["version-update:semver-patch"]