Bump python-dotenv from 0.20.0 to 0.21.0

Bumps [python-dotenv](https://github.com/theskumar/python-dotenv) from 0.20.0 to 0.21.0.
- [Release notes](https://github.com/theskumar/python-dotenv/releases)
- [Changelog](https://github.com/theskumar/python-dotenv/blob/main/CHANGELOG.md)
- [Commits](theskumar/python-dotenv@v0.20.0...v0.21.0)

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

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

Author: dependabot[bot]

requirements.txt

@@ -20,7 +20,7 @@ markupsafe==2.1.1; python_version >= "3.7"
 packaging==21.3; python_version >= "3.6"
 pymysql==1.0.2; python_version >= "3.6"
 pyparsing==3.0.8; python_full_version >= "3.6.8" and python_version >= "3.6"
-python-dotenv==0.20.0; python_version >= "3.5"
+python-dotenv==0.21.0; python_version >= "3.5"
 redis==4.4.0; python_version >= "3.6"
 sqlalchemy==1.4.35; python_version >= "2.7" and python_full_version < "3.0.0" or python_full_version >= "3.6.0"
 webassets==2.0