🧪 Use prefetched action to make trampoline

Previously, the action repository was being cloned from the remote
twice, unnecessarily. This patch eliminates this step and
uses the copy that was checked out on job start.

The generated trampoline action is still copied into the allowlisted
working directory so it can be referenced by the relative path
starting with `./`.

action.yml

@@ -130,24 +130,17 @@ runs:
       PR_REF: ${{ github.event.pull_request.head.ref }}
       PR_REPO: ${{ github.event.pull_request.head.repo.full_name }}
       PR_REPO_ID: ${{ github.event.pull_request.base.repo.id }}
-  - name: Check out action repo
-    uses: actions/checkout@v4
-    with:
-      path: action-repo
-      ref: ${{ steps.set-repo-and-ref.outputs.ref }}
-      repository: ${{ steps.set-repo-and-ref.outputs.repo }}
   - name: Create Docker container action
     run: |
       # Create Docker container action
-      python create-docker-action.py
+      python ${{ github.action_path }}/create-docker-action.py
     env:
       REF: ${{ steps.set-repo-and-ref.outputs.ref }}
       REPO: ${{ steps.set-repo-and-ref.outputs.repo }}
       REPO_ID: ${{ steps.set-repo-and-ref.outputs.repo-id }}
     shell: bash
-    working-directory: action-repo
   - name: Run Docker container
-    uses: ./action-repo/.github/actions/run-docker-container
+    uses: ./.github/.tmp/.generated-actions/run-pypi-publish-in-docker-container
     with:
       user: ${{ inputs.user }}
       password: ${{ inputs.password }}

create-docker-action.py

@@ -10,10 +10,12 @@
 REPO_ID = os.environ['REPO_ID']
 REPO_ID_GH_ACTION = '178055147'
 
+ACTION_SHELL_CHECKOUT_PATH = pathlib.Path(__file__).parent.resolve()
+
 
 def set_image(ref: str, repo: str, repo_id: str) -> str:
     if repo_id == REPO_ID_GH_ACTION:
-        return '../../../Dockerfile'
+        return str(ACTION_SHELL_CHECKOUT_PATH / 'Dockerfile')
     docker_ref = ref.replace('/', '-')
     return f'docker://ghcr.io/{repo}:{docker_ref}'
 
@@ -70,6 +72,9 @@ def set_image(ref: str, repo: str, repo_id: str) -> str:
     },
 }
 
-action_path = pathlib.Path('.github/actions/run-docker-container/action.yml')
+action_path = pathlib.Path(
+    '.github/.tmp/.generated-actions/'
+    'run-pypi-publish-in-docker-container/action.yml',
+)
 action_path.parent.mkdir(parents=True, exist_ok=True)
 action_path.write_text(json.dumps(action, ensure_ascii=False), encoding='utf-8')