Add secret to cache key

To make it possible to invalidate cache if needed

.github/workflows/build.yml

@@ -26,7 +26,9 @@ jobs:
         id: cache
         with:
           path: /tmp/.buildx-cache
-          key: ${{ runner.os }}-buildx-${{ github.sha }}
+          key: ${{ runner.os }}-buildx-${{ secrets.CACHE_KEY }}-${{ github.sha }}
+          restore-keys: |
+            ${{ runner.os }}-buildx-${{ secrets.CACHE_KEY }}-
 
       - name: Set up QEMU
         uses: docker/setup-qemu-action@v1