Migrate icalendar to PyCalendar GitHub organization (was: Nomination to promote two Members to Owners)

[icalendar](https://github.com/collective/icalendar/) is a direct dependency of Plone and one of the few not under the Plone GitHub organization. It is actively maintained and released to both PyPI and GitHub by @niccokunzmann and @SashankBhamidi. I'm an Owner in the Collective GitHub organization. I'd like to nominate them for promotion to Owners in the Collective GitHub organization. I trust them.

The primary reason for this request is to grant them sufficient access to install and configure GitHub apps in icalendar. GitHub permits only Owners to do so for an organization's repositories. We ran into this issue twice, once for Read the Docs and more recently for [Coveralls](https://github.com/collective/icalendar/issues/1556). This would be merely a convenience to the maintainers and Owners in this organization.

The alternative is for maintainers of icalendar to file a request as an issue in this repository and hope that an Owner responds in a timely manner. I personally have done that within the sphinxcontrib organization, and it works OK, but it takes more time and effort to complete routine tasks. It's also difficult to troubleshoot problems with adding or configuring GitHub apps.

Both people are members of the Members Team and the [icalendar-security](https://github.com/orgs/collective/teams/icalendar-security) Team in the Collective GitHub organization. They both have 2FA enabled.

- https://github.com/orgs/collective/people/niccokunzmann
- https://github.com/orgs/collective/people/SashankBhamidi

icalendar might be the only project in the Collective that is more widely used outside of Plone than inside. It's used for home automation, pager duty by LinkedIn, and [hundreds of other projects](https://github.com/collective/icalendar/network/dependents) that require Python to read and write iCalendar files.

Additionally, this could help lay the groundwork for a new policy for promotion of Members to Owners.

Please let me know. Thank you!

Related:
- https://github.com/collective/icalendar/issues/1556
- https://github.com/collective/Collective/issues/1755
- https://github.com/collective/icalendar/pull/1742#discussion_r3918160764

Review the Collective organization membership and team links, related issue icalendar#1556, Collective#1755, and pull request icalendar#1742. Confirm whether the request is to promote the maintainers, move icalendar to a PyCalendar organization, or establish a promotion policy; done means the requested ownership or migration decision is recorded and implemented by an authorized Owner.

Written by the indexing model from the issue text.