use new way to get architecture

.gitea/workflows/container.yaml

@@ -6,15 +6,13 @@ jobs:
     steps:
       - name: Check out repository code
         uses: actions/checkout@v3
-      - name: Set up QEMU
-        uses: docker/setup-qemu-action@v1
       - name: Build image
         id: build-image
         uses: redhat-actions/buildah-build@v2
         with:
           image: docker.io/thallian/alpine-s6
           tags: ${{ gitea.ref_name }} ${{ gitea.sha }} latest
-          archs: amd64
+          archs: amd64, arm64
           containerfiles: |
             ./Containerfile
       - name: Log in to Dockerhub

Containerfile

@@ -1,8 +1,6 @@
 FROM docker.io/alpine:3.19 AS builder
 LABEL maintainer="Sebastian Hugentobler <sebastian@vanwa.ch>"
 
-ARG TARGET_ARCH=x86_64
-
 ENV S6_OVERLAY_VERSION=v3.1.6.2
 
 RUN apk --no-cache add \
@@ -16,8 +14,8 @@ RUN git clone https://github.com/just-containers/s6-overlay.git /src
 WORKDIR /src
 RUN git checkout "$S6_OVERLAY_VERSION"
 
-RUN make ARCH=$TARGET_ARCH-linux-musl -j4
-RUN mv /src/output/rootfs-overlay-${TARGET_ARCH}-linux-musl /src/output/rootfs-overlay-arch
+RUN make ARCH=$(arch)-linux-musl -j4
+RUN mv /src/output/rootfs-overlay-$(arch)-linux-musl /src/output/rootfs-overlay-arch
 
 
 FROM docker.io/alpine:3.19