CI: Remove broken pdf documentation action

See issue: ammaraskar/sphinx-action#32

.github/workflows/docs.yaml

@@ -18,25 +18,3 @@ jobs:
       uses: ammaraskar/sphinx-action@master
       with:
         docs-folder: "docs/"
-
-  docs-pdf:
-    if: |
-      github.event_name == 'pull_request' ||
-      startsWith(github.ref, 'refs/tags/')
-    runs-on: ubuntu-latest
-    steps:
-    - uses: actions/checkout@v2
-
-    - name: Build PDF docs
-      uses: ammaraskar/sphinx-action@master
-      with:
-        docs-folder: "docs/"
-        pre-build-command: "apt-get update -y && apt-get install -y latexmk texlive-latex-recommended texlive-latex-extra texlive-fonts-recommended"
-        build-command: "make latexpdf"
-
-    - uses: actions/upload-artifact@v2
-      if: startsWith(github.ref, 'refs/tags')
-      with:
-        name: Documentation
-        path: docs/_build/latex/*.pdf
-        retention-days: 7