Bump regex from 2020.7.14 to 2020.9.27

Bumps [regex](https://bitbucket.org/mrabarnett/mrab-regex) from 2020.7.14 to 2020.9.27.
- [Commits](https://bitbucket.org/mrabarnett/mrab-regex/commits)

sphinx-doc/requirements_sphinx.txt

@@ -44,7 +44,7 @@ python-intervals==1.10.0
 pytz==2019.3
 PyWavelets==1.1.1
 recommonmark==0.6.0
-regex==2020.7.14
+regex==2020.9.27
 requests==2.24.0
 scikit-learn==0.22.1
 scipy==1.4.1