ci: use podman for container builds

.github/workflows/ci.yaml

@@ -8,17 +8,19 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-      - name: Login to GHCR
-        uses: docker/login-action@v3
+      - uses: actions/checkout@v4
+      - name: Build
+        uses: redhat-actions/buildah-build@v2
         with:
+          image: ${{ github.actor }}/${{ github.event.repository.name }}
+          tags: latest
+          containerfiles: |
+            ./Dockerfile
+      - name: Push
+        uses: redhat-actions/push-to-registry@v2
+        with:
+          image: ${{ github.actor }}/${{ github.event.repository.name }}
+          tags: latest
           registry: ghcr.io
           username: ${{ github.actor }}
           password: ${{ secrets.GITHUB_TOKEN }}
-      - name: Set buildx
-        uses: docker/setup-buildx-action@v3
-      - name: Build and push
-        uses: docker/build-push-action@v5
-        with:
-          push: true
-          tags: |
-            ghcr.io/${{ github.actor }}/${{ github.event.repository.name }}:latest