Bump python-dotenv from 0.20.0 to 0.21.0 in /api

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](https://github.com/theskumar/python-dotenv/compare/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>

api/requirements.txt

@@ -1,8 +1,8 @@
 Flask~=2.1.2
-python-dotenv==0.20.0
+python-dotenv==0.21.0
 uwsgi==2.0.20
 Flask_SQLAlchemy==2.5.1
-python-dotenv==0.20.0
+python-dotenv==0.21.0
 pymysql==1.0.2
 pyjwt==2.3.0
 apiflask==1.0.0