Bump pytz from 2020.4 to 2020.5

Bumps [pytz](https://github.com/stub42/pytz) from 2020.4 to 2020.5.
- [Release notes](https://github.com/stub42/pytz/releases)
- [Commits](https://github.com/stub42/pytz/compare/release_2020.4...release_2020.5)

requirements.txt

@@ -25,7 +25,7 @@ pytest-lazy-fixture==0.6.3
 pytest==6.1.2
 python-dateutil==2.8.1
 python-intervals==1.10.0.post1
-pytz==2020.4
+pytz==2020.5
 PyWavelets==1.1.1
 zipp==3.4.0
 wcwidth==0.2.5