Do not update patch versions for dependabot/github-actions. (#8697)

Towards flutter/flutter#158350.

Author: matanlurey

.github/dependabot.yml

@@ -16,6 +16,11 @@ updates:
       - "team"
       - "team: infra"
       - "autosubmit"
+    # 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"]
 
   # Android example apps.
   - package-ecosystem: "gradle"