Optimise dependencies by adding 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

I want the package to not have an explicit dependency on System.Text.Json as it can be provided by the framework.

Describe alternatives you've considered

Accept the additional dependency

Are you able to help bring it to life and contribute with a Pull Request?

Yes

Additional context

No response