MAINT: Bump pytz from 2020.1 to 2020.4
MAINT: Bump pytz from 2020.1 to 2020.4

Bumps [pytz](https://github.com/stub42/pytz) from 2020.1 to 2020.4.
- [Release notes](https://github.com/stub42/pytz/releases)
- [Commits](https://github.com/stub42/pytz/compare/release_2020.1...release_2020.4)

Signed-off-by: dependabot-preview[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@dependabot.com>
numpy/numpy,jakirkham/numpy,grlee77/numpy,mhvk/numpy,charris/numpy,mattip/numpy,seberg/numpy,pdebuyl/numpy,anntzer/numpy,seberg/numpy,jakirkham/numpy,charris/numpy,rgommers/numpy,mattip/numpy,madphysicist/numpy,anntzer/numpy,mhvk/numpy,simongibbons/numpy,madphysicist/numpy,endolith/numpy,rgommers/numpy,pdebuyl/numpy,grlee77/numpy,numpy/numpy,pbrod/numpy,rgommers/numpy,endolith/numpy,pbrod/numpy,endolith/numpy,endolith/numpy,grlee77/numpy,jakirkham/numpy,pdebuyl/numpy,numpy/numpy,charris/numpy,jakirkham/numpy,simongibbons/numpy,numpy/numpy,mhvk/numpy,pbrod/numpy,simongibbons/numpy,anntzer/numpy,seberg/numpy,madphysicist/numpy,madphysicist/numpy,rgommers/numpy,madphysicist/numpy,grlee77/numpy,seberg/numpy,mattip/numpy,anntzer/numpy,simongibbons/numpy,pbrod/numpy,jakirkham/numpy,mhvk/numpy,charris/numpy,grlee77/numpy,mattip/numpy,pdebuyl/numpy,simongibbons/numpy,pbrod/numpy,mhvk/numpy