chore(docs) improve PDF sidebar and pin dependencies

.github/workflows/compile_docs.yml

@@ -37,7 +37,7 @@ jobs:
         run: sudo apt-get install doxygen texlive-xetex texlive-binaries texlive-lang-english latexmk fonts-freefont-otf
       - name: Install requirements
         run: |
-          pip install --upgrade --upgrade-strategy eager sphinx recommonmark commonmark breathe sphinx-rtd-theme sphinx-markdown-tables sphinx-sitemap
+          pip install --upgrade --upgrade-strategy eager Sphinx==3.5.4 breathe==4.30.0 recommonmark==0.6.0 commonmark==0.9.1 sphinx-rtd-theme==0.5.2 sphinx-markdown-tables==0.0.15 sphinx-sitemap==2.2.0
       - name: Setup Emscripten cache
         id: cache-system-libraries
         uses: actions/cache@v2

docs/conf.py

@@ -169,6 +169,9 @@ latex_elements = {
     'utf8extra': '',
     'classoptions': ',openany,oneside',
     'babel': '\\usepackage{babel}',
+    'passoptionstopackages': r'''
+\PassOptionsToPackage{bookmarksdepth=5}{hyperref}% depth of pdf bookmarks
+''',
     'preamble': r'''
 \usepackage{fontspec}
 \setmonofont{DejaVu Sans Mono}