Add additional TFM do dependencies can be optimised

[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 have additional TFM'S which contains less dependencies. I.e. net core 3 & net 5, this will reduce maintenance effort.

Describe alternatives you've considered Accept the additional dependency

Additional context n/a

[yfakariya]

Which TFMs do you want to support?

I'm thinking to support new TFMs and it looks reasonable to support only net46 (or above), net6, net8 , netstandard2.0, and netstandard2.1. Are they accetable for you?

[thompson-tomo]

What I would propose at a min is:

• drop net standard 1.3
• drop uap
• Drop windows phone
• add net 6
• Add net standard 2.1