Update pelican to 4.1.0

[pyup-bot]

This PR updates pelican from 4.0.1 to 4.1.0.

Changelog

4.1.0

==================

* Live browser reload upon changed files (provided via Invoke task)
* Add ``pyproject.toml``, managed by Poetry
* Support for invoking ``python -m pelican``
* Add relative source path attribute to content
* Allow directories in ``EXTRA_PATH_METADATA``
* Add ``all_articles`` variable to period pages (for recent posts functionality)
* Improve debug mode output
* Remove blank or duplicate summaries from Atom feed
* Fix bugs in pagination, pelican-import, pelican-quickstart, and feed importer

Links

• PyPI: https://pypi.org/project/pelican
• Changelog: https://pyup.io/changelogs/pelican/
• Homepage: https://getpelican.com/

[pyup-bot]

Closing this in favor of #18