Wait for sphinx 3.2.1 I mean.
- Bug#963659: pybind11: FTBFS with Sphinx 3.1: File "/usr/... Drew Parsons
- Bug#963659: pybind11: FTBFS with Sphinx 3.1: File "... Drew Parsons
- Bug#963659: pybind11: FTBFS with Sphinx 3.1: File &q... Drew Parsons
- Bug#963659: pybind11: FTBFS with Sphinx 3.1: Fil... Drew Parsons