Try to work around buildkit bug

Author: BtbN

.github/workflows/build.yml

@@ -24,6 +24,7 @@ jobs:
         uses: docker/setup-buildx-action@v1
         with:
           config: .github/buildkit.toml
+          driver-opts: image=moby/buildkit:v0.9.1
       - name: Login to Docker
         uses: docker/login-action@v1
         with:
@@ -59,6 +60,7 @@ jobs:
         uses: docker/setup-buildx-action@v1
         with:
           config: .github/buildkit.toml
+          driver-opts: image=moby/buildkit:v0.9.1
       - name: Login to Docker
         uses: docker/login-action@v1
         with:
@@ -95,6 +97,7 @@ jobs:
         uses: docker/setup-buildx-action@v1
         with:
           config: .github/buildkit.toml
+          driver-opts: image=moby/buildkit:v0.9.1
       - name: Login to Docker
         uses: docker/login-action@v1
         with:

.github/workflows/pr.yml

@@ -26,6 +26,7 @@ jobs:
         uses: docker/setup-buildx-action@v1
         with:
           config: .github/buildkit.toml
+          driver-opts: image=moby/buildkit:v0.9.1
       - name: Build Image
         run: ./makeimage.sh ${{ matrix.target }} ${{ matrix.variant }}
       - name: Build ffmpeg