Allow newer major Angular versions

[DanielKucal]

Now, when trying to ng update to versions > 8, developers will get the following console error:

Package "angular-ga" has an incompatible peer dependency to "@angular/core" (requires "^8.0.0" (extended), would install "12.1.1"). ✖ Migration failed: Incompatible peer dependencies found.

This PR resolves this. Please create a new npm release as well.

[DanielKucal]

Just realized I've already created exactly the same few months ago 😅