fix: remove version field to work with CI v1.64.8

The golangci-lint-action doesn't properly support v2.1.6 (uses --out-format
flag which v2 doesn't support). Remove version: 2 from config to make it
compatible with CI v1.64.8. Local v2.x will still work but may show a
deprecation warning about the config format.

.github/workflows/ci.yml

@@ -79,9 +79,9 @@ jobs:
           go-version: '1.24'
 
       - name: Run golangci-lint
-        uses: golangci/golangci-lint-action@v4
+        uses: golangci/golangci-lint-action@v3
         with:
-          version: v2.1.6
+          version: v1.64.8
           args: --timeout=5m
 
   build: