chore: Remove pinned golangci-lint version

Let the action use latest version since v9 handles v2.x config properly.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: cv

.github/workflows/ci.yml

@@ -58,8 +58,6 @@ jobs:
 
       - name: Run golangci-lint
         uses: golangci/golangci-lint-action@v9
-        with:
-          version: v2.7.2
 
       - name: Test
         run: go test -race -v ./...