Fix Loading Meetup Data

[tylerdave]

Meetup stopped supporting signed URLs for their APIs so the feeds for event details no longer work. This will likely require:

• a change in this plugin: https://github.com/tylerdave/pelican-meetup-info
• an update to the settings to remove the signed URLs and add the :urlname and credential loading.

[tylerdave]

If this proves too hard to fix we should probably update the homepage to just link to the meetup page for the time being.