fix: add build-celery-worker github action (#3706)

.github/workflows/build-celery-worker.yml

@@ -0,0 +1,45 @@
+name: Build Celery Worker Docker Image
+
+on:
+  push:
+    branches:
+      - 'main'
+    paths:
+      - 'requirements.txt'
+      - 'docker/celery.Dockerfile'
+      - 'docker/scripts/celery-init.sh'
+      - '.github/workflows/build-celery-worker.yml'
+
+  workflow_dispatch: 
+
+jobs:
+  publish:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      packages: write
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Set up QEMU
+      uses: docker/setup-qemu-action@v3
+
+    - name: Set up Docker Buildx
+      uses: docker/setup-buildx-action@v3
+
+    - name: Login to GitHub Container Registry
+      uses: docker/login-action@v3
+      with:
+        registry: ghcr.io
+        username: ${{ github.actor }}
+        password: ${{ secrets.GITHUB_TOKEN }}
+
+    - name: Docker Build & Push
+      uses: docker/build-push-action@v5
+      with:
+        context: .
+        file: docker/celery.Dockerfile
+        platforms: linux/amd64,linux/arm64
+        push: true
+        tags: ghcr.io/ietf-tools/mailarchive-celery:latest