feat(ci): run on real arm64 builders (#1193)

Emulated arm64 builds are slow. Fortunately, GitHub has real Linux ARM64
hardware these days, so let's switch to it.

.github/workflows/docker.yml

@@ -29,13 +29,14 @@ env:
 
 jobs:
  build:
- runs-on: ubuntu-latest
  strategy:
  fail-fast: false
  matrix:
  platform:
- - linux/amd64
- - linux/arm64
+ - ubuntu-latest
+ - github-hosted-ubuntu-arm64
+
+ runs-on: ${{ matrix.platform }}
 
  steps:
  - name: Checkout
@@ -47,9 +48,6 @@ jobs:
  images: ${{ env.REGISTRY_IMAGE }}
  tags: ${{ env.TAGS_CONFIG }}
 
- # Setup buildx
- - name: Set up QEMU
- uses: docker/setup-qemu-action@49b3bc8e6bdd4a60e6116a5414239cba5943d3cf # v3.2.0
  - name: Set up Docker Buildx
  uses: docker/setup-buildx-action@988b5a0280414f521da01fcc63a27aeeb4b104db # v3.6.1
 
@@ -62,7 +60,6 @@ jobs:
  uses: docker/build-push-action@4f58ea79222b3b9dc2c8bbdd6debcef730109a75 # v6.9.0
  with:
  context: .
- platforms: ${{ matrix.platform }}
  labels: ${{ steps.meta.outputs.labels }}
  outputs: type=image,name=${{ env.REGISTRY_IMAGE }},push-by-digest=true,name-canonical=true,push=${{ github.event_name == 'push' }}
 
@@ -93,13 +90,13 @@ jobs:
  - name: Download digests (linux/amd64)
  uses: actions/download-artifact@fa0a91b85d4f404e444e00e005971372dc801d16 # v4.1.8
  with:
- name: digests-linux-amd64
+ name: digests-github-hosted-ubuntu-arm64
  path: /tmp/digests-linux-amd64
 
  - name: Download digests (linux/arm64)
  uses: actions/download-artifact@fa0a91b85d4f404e444e00e005971372dc801d16 # v4.1.8
  with:
- name: digests-linux-arm64
+ name: digests-ubuntu-latest
  path: /tmp/digests-linux-arm64
 
  - name: Merge digests