Bump pytz from 2021.1 to 2021.3 (#1348)

Bumps [pytz](https://github.com/stub42/pytz) from 2021.1 to 2021.3.
- [Release notes](https://github.com/stub42/pytz/releases)
- [Commits](stub42/pytz@release_2021.1...release_2021.3)

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

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