fix: use go-version-file in release workflow

The release workflow hardcoded go-version: "1.25.6", but go.mod was
bumped to 1.25.7 in #316, causing the release to fail with:

  go: go.mod requires go >= 1.25.7 (running go 1.25.6; GOTOOLCHAIN=local)

Switch to go-version-file: "go.mod" to match test.yml, so the version
is always read from go.mod and can't drift.

Author: ethanndickson

.github/workflows/release.yml

@@ -19,7 +19,7 @@ jobs:
       - name: Setup Go
         uses: actions/setup-go@4b73464bb391d4059bd26b0524d20df3927bd417 # v6.3.0
         with:
-          go-version: "1.25.6"
+          go-version-file: "go.mod"
       - name: Import GPG Key
         id: import_gpg
         uses: crazy-max/ghaction-import-gpg@2dc316deee8e90f13e1a351ab510b4d5bc0c82cd # v7.0.0