Fix mock pybind11 in docs

Author: robbievanleeuwen

docs/source/conf.py

@@ -15,7 +15,7 @@
 import os
 import sys
 sys.path.insert(0, os.path.abspath('../../'))
-autodoc_mock_imports = ["meshpy"]
+autodoc_mock_imports = ['pybind11', 'meshpy']
 
 # -- Project information -----------------------------------------------------