Feature/angular update to v17

[PhilipAB]

What kind of change does this PR introduce? (Bug fix, feature, docs update, ...)

• Update to Angular 17 and above
• Updated/removed deprecated packages
• Some minor bug fixes (mainly incorrectly typed functions/variables)
• Fixed CI tests

Does this PR introduce a breaking change?
Yes, requires Angular 17 or higher.

Please check if the PR fulfills these requirements

• This PR is against the develop branch. (Please do not submit PR's to the master branch)
• The commit message follows our guidelines: https://github.com/angular/angular.js/blob/master/CONTRIBUTING.md#commit-message-format
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)
  -> Not sure what the final version numbers will look like. But we could update the Readme.md and encourage people using v5 of this library for Angular versions >= 13 and v6 for Angular versions >= 17.

Other information:
I'm Philip, a contributor of Hobbyfarm, a web-based training plattform. We're using the DateTimePicker within our Admin-UI and while I was updating our project to Angular 17, I did the same for this project :)
I already published a v17-release under my handle, so feel free to test it. You can find it here.