CI: remove matrix build

.github/workflows/ci.yml

@@ -14,10 +14,6 @@ on:
 jobs:
   build:
     runs-on: ubuntu-latest
-    strategy:
-      fail-fast: false
-      matrix:
-        arch: [amd64, arm64]
     steps:
       - uses: actions/checkout@v2
       - name: Set up QEMU
@@ -33,8 +29,8 @@ jobs:
       - name: Build Image
         uses: docker/build-push-action@v2
         with:
-          platforms: linux/${{ matrix.arch }}
+          platforms: linux/amd64,linux/arm64
           push: ${{ (github.ref == 'refs/heads/master') && (github.repository == 'citra-emu/citra-multiplayer-dedicated') }}
           tags: citraemu/citra-multiplayer-dedicated:latest
-          cache-from: type=gha,scope=buildkit-${{ matrix.arch }}
-          cache-to: type=gha,mode=max,scope=buildkit-${{ matrix.arch }}
+          cache-from: type=gha
+          cache-to: type=gha,mode=max