Add QEMU to docker actions to build on more platforms (#273)

This commit adds emulation support with QEMU to be able to build against
more platforms.

Author: maraino

.github/workflows/docker-buildx-push.yml

@@ -44,6 +44,8 @@ jobs:
         with:
           go-version: 'stable'
           check-latest: true
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@c7c53464625b32c7a7e944ae62b3e17d2b600130 # v3.7.0
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@e468171a9de216ec08956ac3ada2f0791b6bd435 # v3.11.1
       - name: Login to Docker Hub