Add labels and group Renovate PRs, run monthly

.github/renovate.json

@@ -0,0 +1,18 @@
+{
+  "$schema": "https://docs.renovatebot.com/renovate-schema.json",
+  "extends": [
+    "config:base"
+  ],
+  "labels": [
+    "changelog: skip",
+    "dependencies"
+  ],
+  "packageRules": [
+    {
+      "groupName": "github-actions",
+      "matchManagers": ["github-actions"],
+      "separateMajorMinor": "false"
+    }
+  ],
+  "schedule": ["on the first day of the month"]
+}

renovate.json

@@ -1,6 +0,0 @@
-{
-  "$schema": "https://docs.renovatebot.com/renovate-schema.json",
-  "extends": [
-    "config:base"
-  ]
-}