ci: activate automerge for github action digest update

Signed-off-by: simonsan <[email protected]>

Author: simonsan

.github/renovate.json

@@ -17,12 +17,22 @@
   ],
   "packageRules": [
     {
+      "description": "Automerge pin updates for GitHub Actions",
       "matchDatasources": [
         "github-actions"
       ],
+      "matchDepTypes": [
+        "action"
+      ],
+      "matchUpdateTypes": [
+        "pin",
+        "digest",
+        "pinDigest"
+      ],
       "labels": [
         "A-ci"
-      ]
+      ],
+      "automerge": true
     }
   ]
-}
+}