Allow GH Actions to build docker images using multi-stage

Allow Github Actions to also build docker images using multi-stage.
Theoretically this can enable building images for linux/arm64 but
as of now there is no publicly available native GH runners for this
architecture.

.github/workflows/github_release_docker.yml

@@ -7,44 +7,23 @@ on:
   workflow_dispatch:
 
 jobs:
-  rust_build:
-    name: Build Nimiq with release flag
-    runs-on: ubuntu-22.04
-    steps:
-      - uses: actions/checkout@v4
-      - uses: dtolnay/rust-toolchain@stable
-      - name: Build binaries in release mode
-        run: |
-          cargo build --release
-      - name: Archive production artifacts
-        uses: actions/upload-artifact@v4
-        with:
-          name: nimiq-dist
-          path: |
-            target/release/nimiq-client
-            target/release/nimiq-bls
-            target/release/nimiq-address
-            target/release/nimiq-rpc
-
   build_docker:
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-24.04
     name: Build & publish docker image
-    needs: rust_build
+    strategy:
+      fail-fast: false
+      matrix:
+        platform:
+          - linux/amd64
+          # As of now, linux/arm64 runners are Qemu based and public native ones will be
+          # available in Q1 2025. See https://github.com/github/roadmap/issues/970.
+          # - linux/arm64
+
     steps:
       - name: Check out the repo
         uses: actions/checkout@v4
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v3
-      - name: Download nimiq client artifact from previous job
-        uses: actions/download-artifact@v4
-        with:
-          name: nimiq-dist
-          path: target/release/
-
-      - name: Run some commands
-        run: |
-          ls target/release/ -al
-          chmod -R +x target/release/
       - name: Docker meta
         id: meta
         uses: docker/metadata-action@v5
@@ -61,6 +40,7 @@ jobs:
           password: ${{ secrets.GITHUB_TOKEN }}
 
       - name: Build and push
+        id: build
         uses: docker/build-push-action@48aba3b46d1b1fec4febb7c5d0c644b249a11355
         with:
           context: .
@@ -76,3 +56,4 @@ jobs:
           labels: ${{ steps.meta.outputs.labels }}
           cache-from: type=gha
           cache-to: type=gha
+          platforms: ${{ matrix.platform }}