2.0.0 with PHP 7.4 support

This is a maintenance release.

• Have introduced PHPStan static analysis
• Upgraded to PHPUnit 9 for PHP 7.4 compatibility
• Upgraded to Laminas from the Zend Diactoros package
• Updated pipeline and removed PHP 7.1 and 7.2, and added 7.4

Retrieve event info for nottingham.digital

Group info:

• group_photo
• group_description

Event info:

• subject - The event title
• description - The event description
• date_time - Kept for BC. e.g "Thursday 12th January 2017 at 7:00pm"
• location - the venue address e.g. "JH, 34a Stoney Street, Nottingham, NG1 1NB, Nottingham"
• event_url - e.g. "https://www.meetup.com/PHPMiNDS-in-Nottingham/events/236134043/",
• iso_date - e.g. "2017-01-12T19:00:00+00:00"

The next_event if exists will have the same structure as the current event.