fix provenance input

When `provenance: false`, we should not set the builder-id.

Signed-off-by: CrazyMax <crazy-max@users.noreply.github.com>

.github/workflows/ci.yml

@@ -523,6 +523,41 @@ jobs:
           file: ./test/go/Dockerfile
           outputs: type=cacheonly
 
+  provenance:
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        attrs:
+          - ''
+          - mode=max
+          - builder-id=foo
+          - false
+          - true
+    steps:
+      -
+        name: Checkout
+        uses: actions/checkout@v3
+      -
+        name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v2
+        with:
+          version: ${{ inputs.buildx-version || env.BUILDX_VERSION }}
+          driver-opts: |
+            network=host
+            image=${{ inputs.buildkit-image || env.BUILDKIT_IMAGE }}
+      -
+        name: Build
+        uses: ./
+        with:
+          context: ./test/go
+          file: ./test/go/Dockerfile
+          target: binary
+          outputs: type=oci,dest=/tmp/build.tar
+          provenance: ${{ matrix.attrs }}
+          cache-from: type=gha,scope=provenance
+          cache-to: type=gha,scope=provenance,mode=max
+
   sbom:
     runs-on: ubuntu-latest
     strategy: