Add Support for .net5.0

[dustinchilson]

When targeting a 5.0 service this library seems to not fully support .net5.0 targets

My library mult-targets netcoreapp3.1 and net5.0 and has issues with the 5.0 build.

I forked and got your lib building just fine on 5.0 off master but noticed you had changes/comments in #43 any issue with a PR adding support for net5.0?

[djluck]

#43 is a long way from being completed- I can add net5.0 as a build target in the meantime- thanks for the report.

[djluck]

v3.4.1 has been published to nuget, should be visible in the next few hours. Thanks again!