Add renovate.json (#4)

Co-authored-by: Renovate Bot <bot@renovateapp.com>

Author: renovate[bot]

renovate.json

@@ -0,0 +1,7 @@
+{
+  "$schema": "http://json.schemastore.org/renovate",
+  "extends": [
+    "github>sourcegraph/renovate-config"
+  ],
+  "semanticCommits": false
+}