fix(ci): don't trigger workflow on pull request

One of the few reasons to support pull_request events is to allow running the GitHub workflow on external pull requests.
That cannot work at the moment, because our GitHub repository URL is hardcoded in `requirements.txt`

.github/workflows/main.yml

@@ -8,9 +8,6 @@ on:
       - "**"
     tags:
       - "v*"
-  pull_request:
-    branches:
-      - "master"
 
 jobs:
   Ansible:
@@ -47,11 +44,6 @@ jobs:
           username: ${{ secrets.DOCKER_USERNAME }}
           password: ${{ secrets.DOCKER_PASSWORD }}
 
-      - name: Extract branch/tag name
-        id: extract_branch
-        shell: bash
-        run: echo "branch=$(echo ${GITHUB_REF/refs\/*\/})" >> $GITHUB_OUTPUT
-
       - name: Build and push
         id: docker_build
         uses: docker/build-push-action@v5
@@ -60,8 +52,7 @@ jobs:
           file: ./docker/Dockerfile
           platforms: linux/amd64,linux/arm64
           push: ${{ github.event_name != 'pull_request' }}
-          build-args: |
-            ANSIBLE_DEPLOY_BRANCH=${{ steps.extract_branch.outputs.branch }}
+          build-args: ANSIBLE_DEPLOY_BRANCH=${{ github.ref_name }}
           tags: ${{ steps.docker_meta.outputs.tags }}
           labels: ${{ steps.docker_meta.outputs.labels }}