Update renovate config to bundle updates into single PRs

To remove the amount of PRs we are receiving from renovate, the config
has been updated to bundle all docker image digest updats into a single
PR. Additionally, all github action updates are now also in a single PR.

renovate.json → renovate.json5

@@ -22,6 +22,23 @@
       ],
       "groupName": "all non-major dependencies",
       "groupSlug": "all-minor-patch"
+    },
+    {
+      "matchDatasources": [
+        "docker",
+      ],
+      "matchUpdateTypes": [
+        "digest",
+      ],
+      "groupName": "all image digest updates",
+      "groupSlug": "all-image-digest-updates"
+    }
+    {
+      "matchManagers": [
+        "github-actions",
+      ],
+      "groupName": "github actions",
+      "groupSlug": "github-actions"
     }
   ]
 }