Bump pytz from 2020.1 to 2021.1

Bumps [pytz](https://github.com/stub42/pytz) from 2020.1 to 2021.1.
- [Release notes](https://github.com/stub42/pytz/releases)
- [Commits](stub42/pytz@release_2020.1...release_2021.1)

---
updated-dependencies:
- dependency-name: pytz
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

requirements.txt

@@ -58,7 +58,7 @@ pytest-mock==3.6.1
     # via -r requirements.in
 python-dateutil==2.8.2
     # via croniter
-pytz==2020.1
+pytz==2021.1
     # via -r requirements.in
 redis==3.5.3
     # via -r requirements.in