Removed mijntuin since mijntuin.org stops activities

[myTselection]

Checklist

• [X] I've read the publishing documentation.
• [X] I've added the HACS action to my repository.
• [X] (For integrations only) I've added the hassfest action to my repository.
• [X] The actions are passing without any disabled checks in my repository.
• [X] I've added a link to the action run on my repository below in the links section.
• [X] I've created a new release of the repository after the validation actions were run successfully.

Links

Link to current release: https://github.com/myTselection/MijnTuin/releases Link to successful HACS action (without the ignore key): https://github.com/myTselection/MijnTuin/actions/workflows/hacs_action.yml Link to successful hassfest action (if integration): https://github.com/myTselection/MijnTuin/actions/workflows/hassfest_validation.yml