Fix container workflow: build wheel before Docker, update deprecated syntax

- Replace removed ::set-output with GITHUB_OUTPUT
- Add fetch-depth: 0 so lsst-versions can read git tags when building wheel
- Add Python + build step to produce dist/*.whl before docker build
- Update docker/login-action v1 -> v3

Generated with AI

Co-Authored-By: SLAC AI

Author: ebellm

.github/workflows/build_sync_container.yml

@@ -21,16 +21,28 @@ jobs:
       || startsWith(github.head_ref, 'tickets/')
 
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
 
       - name: Define the Docker tag
         id: vars
-        run: echo ::set-output name=tag::$(script/docker-tag.sh "$GITHUB_REF")
+        run: echo "tag=$(script/docker-tag.sh "$GITHUB_REF")" >> "$GITHUB_OUTPUT"
 
       - name: Print the tag
         id: print
         run: echo ${{ steps.vars.outputs.tag }}
 
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: "3.12"
+
+      - name: Build wheel
+        run: |
+          pip install --upgrade build
+          python -m build --wheel --skip-dependency-check
+
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v3
 
@@ -43,7 +55,7 @@ jobs:
             ${{ runner.os }}-buildx-
 
       - name: Log in to Docker Hub
-        uses: docker/login-action@v1
+        uses: docker/login-action@v3
         with:
           username: ${{ secrets.DOCKER_HUB_USERNAME }}
           password: ${{ secrets.DOCKER_HUB_ACCESS_TOKEN }}