Update project's Angular version

[Lehoczky]

The current Angular version used in this repository (19) is few major versions behind the latest (22).

Would you accept a PR updating Angular without affecting the library's compatibility? Even if not the latest, but to the next major.

[macjohnny]

yes, we can upgrade to the latest angular version that still builds a package compatible with the currently listed compatible versions in https://github.com/bithost-gmbh/ngx-mat-select-search/blob/master/README.md#current-release

this involves manual testing using the example app https://github.com/bithost-gmbh/ngx-mat-select-search-example