CI: disable VCS stamping in containerized build

git inside the golang container flags the mounted repo as dubious
ownership (different UID), so `go build` fails obtaining VCS status
(exit 128). The binary doesn't need git version stamping here.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.forgejo/workflows/build.yml

@@ -10,7 +10,7 @@ jobs:
       - name: Test
         run: docker run --rm -w /src -v $PWD:/src golang:1.26 go test ./...
       - name: Build
-        run: docker run --rm -w /src -v $PWD:/src -e CGO_ENABLED=0 golang:1.26 go build -ldflags "-s -w" -o hsa ./cmd/hsa
+        run: docker run --rm -w /src -v $PWD:/src -e CGO_ENABLED=0 golang:1.26 go build -buildvcs=false -ldflags "-s -w" -o hsa ./cmd/hsa
       - name: Upload binary
         uses: actions/upload-artifact@v3
         with: