Add multiple architechture build support

Add auto builds for x86, x86_64, and arm64

.github/workflows/docker.yml

@@ -13,6 +13,9 @@ jobs:
       - name: 'Checkout GitHub Action'
         uses: actions/checkout@v2
 
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v1
+
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v1
 
@@ -37,4 +40,5 @@ jobs:
         uses: docker/build-push-action@v2
         with:
           push: true
+          platforms: linux/amd64,linux/arm64,linux/386
           tags: esanchezm/prometheus-qbittorrent-exporter:latest,esanchezm/prometheus-qbittorrent-exporter:${{ steps.extract_branch.outputs.tag }}