Move renovate.json to .github folder (#2367)

.github/renovate.json

@@ -0,0 +1,25 @@
+{
+  "$schema": "https://docs.renovatebot.com/renovate-schema.json",
+  "extends": [
+    "config:base",
+    "schedule:monthly",
+    ":maintainLockFilesMonthly",
+    ":preserveSemverRanges",
+    ":rebaseStalePrs",
+    ":disableMajorUpdates"
+  ],
+  "enabledManagers": [
+    "nuget"
+  ],
+  "packageRules": [
+    {
+      "matchManagers": ["nuget"],
+      "groupName": "Nuget updates",
+      "groupSlug": "nuget",
+      "matchUpdateTypes": [
+        "minor",
+        "patch"
+      ]
+    }
+  ]
+}