Iga

Changes in this release:
* Fixed [issue 28](https://github.com/caltechlibrary/iga/issues/28): catch and report the case where a repo has no releases.
* Fixed a bug that manifested when the GitHub access token was invalid.
* Fixed a syntax bug in the Makefile.
* Improved (hopefully) the caching of python dependencies to actually work this time.
* Improved (hopefully) some of the diagnostic error messages.
* Added Tom Morrell to the CITATION.cff file.

Changes in this release:
* Fixed `setup.cfg`, which had some garbled content.
* Fixed the GitHub Action for building the IGA documentation pages to avoid needlessly running it on every push.
* The GitHub Actions workflow (`action.yml`) for IGA now caches Python package dependencies for a slight speed up in run times on GitHub.
* Added a GitHub Actions workflow to lint the code on pushes & pull requests.

This version fixes problems with handling Invenio Communities. First, an internal bug in IGA would cause an exception if the user attempted to list communities in an InvenioRDM server that defined more than one community. Second, a bug in InvenioRDM itself meant that community links were broken. (Thanks to tmorrell for a fix via PR 23.)

Additional changes in this version:
* Switched to using `codemeta.json` as the main source of truth for version info. The `setup.cfg` file is now updated from `codemeta.json`, not the other way around.
* With respect to how the InvenioRDM metadata field `related_identifiers` is handled, the IGA [documentation](https://caltechlibrary.github.io/iga/appendix.html#record-metadata) and the [Google spreadsheet describing how IGA maps fields](https://docs.google.com/spreadsheets/d/1QgFrZIhip1qKA_M45QkeYe9SH238XL1K/edit?usp=sharing&ouid=111701691832013929970&rtpof=true&sd=true) both omitted the use of CodeMeta fields `downloadUrl` and `installUrl` and CFF field `repository-artifact`. These fields are now in the documentation.
* The Makefile has been updated in various ways based on experiences with other projects.

New features:
* New option `--print-doi` makes IGA print the DOI of a published record in addition to printing the URL. (Without the option, IGA only prints the URL.)

Changes:
* The color of text messages printed to the terminal has been changed slightly in an effort to improve readability.
* The versions of some dependencies in `requirements.txt` have been updated.
* Documentation has been updated and expanded.

Changes in this release:
* The sample workflow has been revised to be slightly more informative about where it's sending the release for archiving.

Changes in this release:
* Fix issue 21: the copyright year put in the metadata `dates` field can could up being a completely bogus value in some cases.