build: remove "build" target from Makefile

You can invoke directly "make linux/arm"

.github/workflows/plugins.yml

@@ -42,8 +42,21 @@ jobs:
       - name: Checkout code
         uses: actions/checkout@v2
 
-      - name: Build Local Docker image for tests
-        run: docker build -t ghcr.io/acouvreur/sablier:local .
-        
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v2
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v2
+        with:
+          version: latest
+          buildkitd-flags: --debug
+      -
+        name: Build and push
+        id: docker_build
+        uses: docker/build-push-action@v2
+        with:
+          context: .
+          tags: ghcr.io/acouvreur/sablier:local
+
       - name: Test ${{ matrix.provider }}
         run: cd plugins/traefik/e2e && bash ./${{ matrix.provider }}.sh