[ci] Configure GOFLAGS when cross-compiling release binaries

.github/workflows/release.yml

@@ -19,6 +19,7 @@ jobs:
     - name: Publish release script
       run: script/publish-release
       env:
+        GOFLAGS: -mod=vendor
         GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
 
     - uses: mislav/bump-homebrew-formula-action@v1.4