ci: fetch full history in golangci-lint job

revgrep needs pull_request.base.sha in the local clone to compute
the diff against new code. With fetch-depth: 2, only HEAD and one
parent are fetched, so a stale base SHA (when main moves between
PR syncs) is not reachable and revgrep falls through, surfacing
pre-existing issues outside the PR scope.

.github/workflows/lint.yml

@@ -12,7 +12,7 @@ jobs:
     steps:
       - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
         with:
-          fetch-depth: 2
+          fetch-depth: 0
       - name: Get changed files
         id: changed-files
         uses: dorny/paths-filter@de90cc6fb38fc0963ad72b210f1f284cd68cea36 # v3.0.2