Fix go-lint-checks CI job failures (#537)

With the [release of go1.26](https://go.dev/blog/go1.26), CI started
failing the golangci-lint job because actions/setup-go was configured
with go-version: stable, which now selects go1.26. Our pinned
golangci-lint binary (v2.6.1, built with go1.25) is not compatible with
go1.26.

This change switches the workflow to use
[go-version-file](https://github.com/actions/setup-go#go-version-file):
go.mod, so checks consistently run with Pebble’s Go version. Note: we
will still need to need to update golangci-lint when we move Pebble to
go1.26, but this isn't a step we need to take right now.

Author: beautifulentropy

.github/workflows/checks.yml

@@ -11,7 +11,6 @@ permissions:
   pull-requests: read
 env:
   CGO_ENABLED: 0
-  GO_VERSION: stable
   GOLANGCI_LINT_VERSION: v2.6.1
   SHELLCHECK_SCRIPTS: ./*.sh
 jobs:
@@ -21,7 +20,7 @@ jobs:
       - uses: actions/checkout@v5
       - uses: actions/setup-go@v6
         with:
-          go-version: ${{ env.GO_VERSION }}
+          go-version-file: go.mod
       - name: Run GolangCI-Lint
         uses: golangci/golangci-lint-action@v9
         with:
@@ -32,7 +31,7 @@ jobs:
       - uses: actions/checkout@v5
       - uses: actions/setup-go@v6
         with:
-          go-version: ${{ env.GO_VERSION }}
+          go-version-file: go.mod
       - name: Check if go.mod is tidy
         run: |
           go mod tidy