Reserve Renovate slots for automerge branches

.github/renovate.json

@@ -7,7 +7,8 @@
   "labels": [
     "dependencies"
   ],
-  "branchConcurrentLimit": 3,
+  "branchConcurrentLimit": 5,
+  "prConcurrentLimit": 3,
   "hostRules": [
     {
       "matchHost": "https://mau.dev",