Bump pytz from 2020.5 to 2021.1

Bumps [pytz](https://github.com/stub42/pytz) from 2020.5 to 2021.1.
- [Release notes](https://github.com/stub42/pytz/releases)
- [Commits](https://github.com/stub42/pytz/compare/release_2020.5...release_2021.1)

requirements.txt

@@ -25,7 +25,7 @@ pytest-lazy-fixture==0.6.3
 pytest==6.2.2
 python-dateutil==2.8.1
 python-intervals==1.10.0.post1
-pytz==2020.5
+pytz==2021.1
 PyWavelets==1.1.1
 zipp==3.4.0
 wcwidth==0.2.5