Bump pytz from 2021.1 to 2021.3

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
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

requirements.in

@@ -7,7 +7,7 @@ pbr==1.10.0
 protobuf==3.19.3
 pyopenssl==19.1.0
 PyYAML==5.2 # PyYAML 5.3 does not support Python 3.4
-pytz==2021.1
+pytz==2021.3
 requests>=2.20.0
 urllib3>=1.24.3
 deprecated==1.2.13