remove Docker arm/v7 auto-builds, rename :main to :stable

.github/workflows/docker.yml

@@ -31,7 +31,7 @@ jobs:
         with:
           version: latest
           install: true
-          platforms: linux/amd64,linux/arm64,linux/arm/v7
+          platforms: linux/amd64,linux/arm64
 
       - name: Builder instance name
         run: echo ${{ steps.buildx.outputs.name }}
@@ -55,16 +55,22 @@ jobs:
           password: ${{ secrets.DOCKER_PASSWORD }}
 
       - name: Collect Docker tags
+        # https://github.com/docker/metadata-action
         id: docker_meta
         uses: docker/metadata-action@v5
         with:
           images: archivebox/archivebox,nikisweeting/archivebox
           tags: |
+              # :stable
               type=ref,event=branch
+              # :0.7.3
               type=semver,pattern={{version}}
+              # :0.7
               type=semver,pattern={{major}}.{{minor}}
+              # :sha-463ea54
               type=sha
-              type=raw,value=latest,enable={{is_default_branch}}
+              # :latest
+              type=raw,value=latest,enable=${{ github.ref == format('refs/heads/{0}', 'stable') }}
 
       - name: Build and push
         id: docker_build
@@ -77,7 +83,7 @@ jobs:
           tags: ${{ steps.docker_meta.outputs.tags }}
           cache-from: type=local,src=/tmp/.buildx-cache
           cache-to: type=local,dest=/tmp/.buildx-cache-new
-          platforms: linux/amd64,linux/arm64,linux/arm/v7
+          platforms: linux/amd64,linux/arm64
 
       - name: Image digest
         run: echo ${{ steps.docker_build.outputs.digest }}