fix: enable Renovate auto-updates for go directive in go.mod

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: koki-develop

renovate.json

@@ -8,6 +8,12 @@
     {
       "matchFileNames": ["Dockerfile"],
       "semanticCommitType": "fix"
+    },
+    {
+      "matchManagers": ["gomod"],
+      "matchDepNames": ["go"],
+      "matchDepTypes": ["golang"],
+      "rangeStrategy": "bump"
     }
   ]
 }