Update python-dotenv requirement from ==0.19.* to >=0.19,<0.21

Updates the requirements on [python-dotenv](https://github.com/theskumar/python-dotenv) to permit the latest version.
- [Release notes](https://github.com/theskumar/python-dotenv/releases)
- [Changelog](https://github.com/theskumar/python-dotenv/blob/master/CHANGELOG.md)
- [Commits](theskumar/python-dotenv@v0.19.0...v0.20.0)

---
updated-dependencies:
- dependency-name: python-dotenv
  dependency-type: direct:development
...

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

setup.py

@@ -32,7 +32,7 @@
               "pylint==2.12.*",
               'pytest==7.1.1',
               'pytest-cov==3.0.0',
-              "python-dotenv==0.19.*"
+              "python-dotenv>=0.19,<0.21"
           ]
       },
       entry_points="""