keyring v21.0.0

[regro-cf-autotick-bot]

It is very likely that the current package version for this feedstock is out of date. Notes for merging this PR:

1. Feel free to push to the bot's branch to update this PR if needed.
2. The bot will almost always only open one PR per version. Checklist before merging this PR:
   • [ ] Dependencies have been updated if changed
   • [ ] Tests have passed
   • [ ] Updated license if changed and license_file is packaged

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If this PR was opened in error or needs to be updated please add the bot-rerun label to this PR. The bot will close this PR and schedule another one.

_{This PR was created by the cf-regro-autotick-bot. The cf-regro-autotick-bot is a service to automatically track the dependency graph, migrate packages, and propose package version updates for conda-forge. If you would like a local version of this bot, you might consider using rever. Rever is a tool for automating software releases and forms the backbone of the bot's conda-forge PRing capability. Rever is both conda (conda install -c conda-forge rever) and pip (pip install re-ver) installable. Finally, feel free to drop us a line if there are any issues! This PR was generated by https://circleci.com/gh/regro/circle_worker/13105, please use this URL for debugging}

[conda-forge-linter]

Hi! This is the friendly automated conda-forge-linting service.

I just wanted to let you know that I linted all conda-recipes in your PR (recipe) and found it was in an excellent condition.