fix: use svg to pdf converter instead of original solution

docs/conf.py

@@ -31,7 +31,7 @@ import subprocess
 # Add any Sphinx extension module names here, as strings. They can be
 # extensions coming with Sphinx (named 'sphinx.ext.*') or your custom
 # ones.
-extensions = ['breathe', 'sphinx.ext.imgconverter']
+extensions = ['breathe', 'sphinxcontrib.rsvgconverter']
 
 breathe_projects = {'pybind11': '.build/doxygenxml/'}
 breathe_default_project = 'pybind11'

docs/requirements.txt

@@ -3,3 +3,4 @@ commonmark==0.9.1
 recommonmark==0.6.0
 sphinx==3.2.1
 sphinx_rtd_theme==0.5.0
+sphinxcontrib-svg2pdfconverter==1.1.0