ci: add renovate.json

Author: sciyoshi

.github/renovate.json5

@@ -0,0 +1,7 @@
+{
+  "$schema": "https://docs.renovatebot.com/renovate-schema.json",
+  "extends": [
+    "config:recommended",
+    ":disableDependencyDashboard",
+  ]
+}