[PyUP] Update feedgenerator to 2.1.0

[pyup-bot]

This PR updates feedgenerator from 2.0.0 to 2.1.0.

Changelog

2.1.0

------------------

* Modernize and improve tests ([32](https://github.com/getpelican/feedgenerator/pull/32) & [#34](https://github.com/getpelican/feedgenerator/pull/34) — thanks to venthur)
* Drop support for Python 3.6 and test on 3.10 & 3.11 ([35](https://github.com/getpelican/feedgenerator/pull/35) — thanks to hugovk)
* Exclude `tests_feedgenerator/__pycache__` from distribution ([33](https://github.com/getpelican/feedgenerator/pull/33) — thanks to BenSturmfels)

Links

• PyPI: https://pypi.org/project/feedgenerator
• Changelog: https://pyup.io/changelogs/feedgenerator/
• Repo: https://github.com/getpelican/feedgenerator

[pyup-bot]

Closing this in favor of #237