[CI] Download fixed versions of Python tools (#1485)

Download particular versions of Sphinx and plugins instead of using the
latest available versions on the repository.

Signed-off-by: Alexander Batashev <alexander.batashev@intel.com>

Author: Alexander Batashev

.github/workflows/gh_pages.yml

@@ -15,7 +15,7 @@ jobs:
     - name: Install deps
       run: |
         sudo apt-get install -y doxygen graphviz ssh ninja-build
-        sudo pip3 install sphinx recommonmark sphinx_markdown_tables
+        sudo pip3 install 'sphinx==3.0.0' 'recommonmark==0.6.0' 'sphinx_markdown_tables==0.0.12'
     - name: Build Docs
       run: |
         mkdir -p $GITHUB_WORKSPACE/build

sycl/doc/conf.py

@@ -32,6 +32,7 @@
 # extensions coming with Sphinx (named 'sphinx.ext.*') or your custom
 # ones.
 extensions = [
+    'recommonmark',
     'sphinx_markdown_tables'
 ]