Add extension to generate a table of future meeting dates and times

[StanFromIreland]

This expands a little on #185, adding an extension to automatically generate a list of upcoming meetings, and an iCal.

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📚 Documentation preview 📚: https://docs-community--186.org.readthedocs.build/community/monthly-meeting.html

[hugovk]

Please can you fix the validation errors, for example from https://icalendar.org/validator.html.html?url=https://docs-community--186.org.readthedocs.build/docs-community-meetings.ics ?

Errors
Missing DTSTAMP property [near line # 4](javascript:void(0);)
Reference: [RFC 5545 3.6.1. Event Component](http://icalendar.org/iCalendar-RFC-5545/3-6-1-event-component.html)
Missing UID property [near line # 4](javascript:void(0);)
Reference: [RFC 5545 3.6.1. Event Component](http://icalendar.org/iCalendar-RFC-5545/3-6-1-event-component.html)
Missing DTSTAMP property [near line # 10](javascript:void(0);)
Reference: [RFC 5545 3.6.1. Event Component](http://icalendar.org/iCalendar-RFC-5545/3-6-1-event-component.html)
Missing UID property [near line # 10](javascript:void(0);)
Reference: [RFC 5545 3.6.1. Event Component](http://icalendar.org/iCalendar-RFC-5545/3-6-1-event-component.html)
Missing DTSTAMP property [near line # 16](javascript:void(0);)
Reference: [RFC 5545 3.6.1. Event Component](http://icalendar.org/iCalendar-RFC-5545/3-6-1-event-component.html)
Missing UID property [near line # 16](javascript:void(0);)
Reference: [RFC 5545 3.6.1. Event Component](http://icalendar.org/iCalendar-RFC-5545/3-6-1-event-component.html)
Missing DTSTAMP property [near line # 22](javascript:void(0);)
Reference: [RFC 5545 3.6.1. Event Component](http://icalendar.org/iCalendar-RFC-5545/3-6-1-event-component.html)
Missing UID property [near line # 22](javascript:void(0);)
Reference: [RFC 5545 3.6.1. Event Component](http://icalendar.org/iCalendar-RFC-5545/3-6-1-event-component.html)
Missing DTSTAMP property [near line # 28](javascript:void(0);)
Reference: [RFC 5545 3.6.1. Event Component](http://icalendar.org/iCalendar-RFC-5545/3-6-1-event-component.html)
Missing UID property [near line # 28](javascript:void(0);)
Reference: [RFC 5545 3.6.1. Event Component](http://icalendar.org/iCalendar-RFC-5545/3-6-1-event-component.html)
Missing DTSTAMP property [near line # 34](javascript:void(0);)
Reference: [RFC 5545 3.6.1. Event Component](http://icalendar.org/iCalendar-RFC-5545/3-6-1-event-component.html)
Missing UID property [near line # 34](javascript:void(0);)
Reference: [RFC 5545 3.6.1. Event Component](http://icalendar.org/iCalendar-RFC-5545/3-6-1-event-component.html)

We also have iCal creation in the PEPs repo in case that's helpful (I guess you already checked).

And maybe add type annotations?

[hugovk]

It'll be very useful to have an auto-updating iCal, thanks!

Maybe we no longer need the manually updated Google calendar meeting?

[StanFromIreland]

Please can you fix the validation errors,

Green now, I had only tested with my calendar, thanks for checking!

And maybe add type annotations?

We don't have any type-checking currently, and that's not something I'm particularly interested in setting up (I'm not a fan of types;-), if you really want them, I can add some.

It'll be very useful to have an auto-updating iCal, thanks!

Indeed, I've always found the current annoying having to add them manually, especially now with the time variations.

[willingc]

Love this! Thanks @StanFromIreland. Once @hugovk is satisfied, 🚢