Optimise dependencies based on TFM

[thompson-tomo]

Is your feature request related to a problem? Please describe.
I want to minimise dependencies in my project by utilising framework dependencies wherever possible

Describe the solution you'd like
The aspnet package needs to have the dependencies optimised to duplicate packages provided by the asp net framework. System.Text.Json should only be included on net standard 2.1.

Describe alternatives you've considered
Accept the additional dependency

Additional context
n/a