Try removing deprecated call to get_html_theme_path

docs/source/conf.py

@@ -244,7 +244,6 @@ def __call__(self, filename):
 # html_theme = 'default'
 # html_theme = "sphinxdoc"
 html_theme = "sphinx_rtd_theme"
-html_theme_path = [sphinx_rtd_theme.get_html_theme_path()]
 
 # Theme options are theme-specific and customize the look and feel of a theme
 # further.  For a list of options available for each theme, see the
@@ -260,9 +259,6 @@ def __call__(self, filename):
     'css/custom.css',
 ]
 
-# Add any paths that contain custom themes here, relative to this directory.
-# html_theme_path = []
-
 # The name for this set of Sphinx documents.  If None, it defaults to
 # "<project> v<release> documentation".
 # html_title = None