Support .netcoreapp3.*

What's Changed

• feat!: migrate Newtonsoft.Json to System.Text.Json by @nogic1008 in #3

New Contributors

• @nogic1008 made their first contribution in #3

Full Changelog: archive-support-netcoreapp2.0...3.0.0

archive-support-netcoreapp2.*

Full Changelog: https://github.com/Nongzhsh/Awesome.Net.WritableOptions/commits/archive-support-netcoreapp2.0