Staticcheck action broken

[findleyr]

Example: https://github.com/modelcontextprotocol/go-sdk/actions/runs/18723413710/job/53401716305?pr=594

The staticcheck github action seems to have started failing. I'm not sure what changed, but after tweaking the action configuration, I was able to see errors:
https://github.com/modelcontextprotocol/go-sdk/actions/runs/18724340263/job/53404922029?pr=597

(I don't know why these settings show actionable logs, and the first does not).

Needs to be investigated and fixed promptly, or disabled.

[findleyr]

Fixed by #598.