Angular 20 upgrade

[mohammedsahl]

Closes #131

Hello 👋

This PR upgrades the angular version to 20. More about it here https://blog.angular.dev/announcing-angular-v20-b5c9c06cf301

[mohammedsahl]

I've made sure to run

yarn run:demon
yarn build:demo
yarn build:library
yarn test
yarn lint

Let me know if there's anything else I should verify. Thank you :)

[timofei-iatsenko]

Does the compiled code still compatible with a 19 version? If yes - then constraint here should be widened not just bumped to 20.

eq: "@angular/common": "^19 || ^20",

Also there is no sense to narrow constraint to 20.3.13, it should work well with every 20.x version right?

[mohammedsahl]

I've changed it now. I tested by changing the demo app's version to 19, running tests, then smoke testing the app itself manually. It seems to work.

Although I do want to note that the peer deps before for @angular/common and @angular/core were both ^19.1.4. I've changed it to ^19.0.0 || ^20.0.0. Meaning it's even less restrictive than the previous version.

To me that seems fine. Let me know if I should revert back to the more restrictive "^19.1.4".