ci: remove auto-doxygen workflow

Le workflow régénérait un fichier doc/QElectroTech.qch de ~500 Mo à
chaque push de tag (y compris le tag nightly), ce qui a fait grimper
la conso mensuelle de bande passante Git LFS de l'organisation
qelectrotech à 90% du quota.

.github/workflows/auto-doxygen.yml

@@ -1,67 +0,0 @@
-name: Auto-build doxygen docs
-on:
-  push:
-    tags:
-       - '**'
-   
-  
-  
-jobs:  
-  doxygen:
-    permissions:
-       contents: write    
-    runs-on: ubuntu-latest
-    steps:
-    - uses: actions/checkout@v4
-      with:
-        submodules: 'recursive'
-        show-progress: ''
-    - name: Setup and run doxygen
-      run: sudo apt update && sudo apt install doxygen graphviz qhelpgenerator-qt5 -y
-    - name: Set up Git LFS
-      run: |
-          git lfs install
-          git lfs track "*.qch"  
-    - name: Run doxygen
-      run: doxygen Doxyfile
-    - name: Create Pull Request
-      uses: peter-evans/create-pull-request@v8
-      with:
-        token: ${{ secrets.MR_TOKEN }}
-        commit-message: update QCH file
-        committer: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
-        title: Update QCH Help file
-        body: |
-         - Updating QT Help file following commit ${{ github.sha }}.
-         - Auto-generated by [create-pull-request][1]
-
-         [1]: https://github.com/peter-evans/create-pull-request
-        branch: update-qch
-        labels: | 
-          qch
-          cicd
-        delete-branch: true
-        add-paths: doc/*.qch
-    - uses: actions/upload-pages-artifact@v3
-      with: 
-       path: ${{ github.workspace }}/doc/html/
-  deploy:
-    # Add a dependency to the build job
-    needs: doxygen
-
-    # Grant GITHUB_TOKEN the permissions required to make a Pages deployment
-    permissions:
-      pages: write      # to deploy to Pages
-      id-token: write   # to verify the deployment originates from an appropriate source
-
-    # Deploy to the github-pages environment
-    environment:
-      name: github-pages
-      url: ${{ steps.deployment.outputs.page_url }}
-
-    # Specify runner + deployment step
-    runs-on: ubuntu-latest
-    steps:
-      - name: Deploy to GitHub Pages
-        id: deployment
-        uses: actions/deploy-pages@v4 # or specific "vX.X.X" version tag for this action