Do not update patch versions for dependabot/github-actions. (#1412)

Towards flutter/flutter#158350.

Author: matanlurey

.github/dependabot.yaml

@@ -5,6 +5,11 @@ updates:
     directory: "/"
     schedule:
       interval: "daily"
+    # 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"]
   - package-ecosystem: "npm"
     directory: "/docs"
     schedule: