Configure automerge for renovate

Signed-off-by: Nick Slowinski <nick@nick-slowinski.de>

renovate.json

@@ -15,6 +15,16 @@
         "minor",
         "major"
       ]
+    },
+    {
+      "matchUpdateTypes": [
+        "minor",
+        "patch",
+        "pin",
+        "digest"
+      ],
+      "automerge": true,
+      "automergeStrategy": "fast-forward"
     }
   ],
   "reviewers": [