github/workflows: Build x86 + arm64 Yetus images at once

Unfortunately the job matrix cannot be used to build Yetus image because
the job that finishes last will overwrite the image pushed to dockerhub.
Since only x86 runners are used to build this image, there is no need to
complicate the handling of manifests. Instead, we can just build and push
both images at once. The parallelism in this case is not critical at all.

Signed-off-by: Renê de Souza Pinto <rene@renesp.com.br>

Author: rene

.github/workflows/buildyetusondemand.yml

@@ -34,8 +34,6 @@ jobs:
       IMG_TAG: "0.15.1-eve-1"
     strategy:
       fail-fast: false
-      matrix:
-        arch: [amd64, arm64]
 
     steps:
       - name: Starting Report
@@ -52,6 +50,8 @@ jobs:
           ref: ${{ github.event.pull_request.head.ref }}
           fetch-depth: 0
           persist-credentials: false
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
       - name: Login to Docker Hub
         if: ${{ env.REPO_NAME == 'lf-edge/eve' }}
         uses: docker/login-action@5e57cd118135c172c3672efd75eb46360885c0ef  # v3.6.0
@@ -60,7 +60,7 @@ jobs:
           password: ${{ secrets.RELEASE_DOCKERHUB_TOKEN }}
       - name: Build and push Yetus image
         run: |
-          docker buildx build --platform linux/${{ matrix.arch }} --push --tag ${{ env.IMG_NAME }}:${{ env.IMG_TAG }} tools/yetus
+          docker buildx build --platform linux/amd64,linux/arm64 --push --tag ${{ env.IMG_NAME }}:${{ env.IMG_TAG }} tools/yetus
       - name: Post package report
         run: |
           echo Disk usage