renovate: automerge digest-level image updates

renovate.json

@@ -14,5 +14,13 @@
       "depNameTemplate": "yt-dlp/yt-dlp",
       "versioningTemplate": "regex:^(?<major>\\d{4})\\.(?<minor>\\d{2})\\.(?<patch>\\d{2})$"
     }
+  ],
+  "packageRules": [
+    {
+      "description": "Automerge digest-level image updates",
+      "matchUpdateTypes": ["digest"],
+      "groupName": "all-minor-patch-updates",
+      "automerge": true
+    }
   ]
 }