Meetup reminders are still send to people who left the server the meetup is in

[Sheldan]

General Troubleshooting

• I have checked for similar issues on the Issue-tracker.
• I have updated to the latest version
• I have checked the branches or the maintainers' PRs for upcoming bug fixes.

Description

If a meetup reminder is sent, it is not checked if the user has left the server the meetup was in.

Steps to reproduce

Create a meetup
Have another user (B) participate in it
The other user (B) leaves the server

Expected behaviour

The bot should not remind the user who left

Actual behaviour

The bot does remind the user who left