Add .Net Core 5.0 - 6.0 support

[areis422]

Is your feature request related to a problem? Please describe.
No problem

Describe the solution you'd like
Update code to be compatible with .Net Core 5.0 to keep things up to date and future proof.

[simonai1254]

Hi areis

Runtime 5.0 is already supported, you might need to have a look at #615 on how to get it running with the current build.
But I'm with you that one should create a new build that defaults to 5.0 and not to 3.1.0

Regards
Simon

[areis422]

I'd be looking for a second zip w/ Code that will run on .Net 5 vs having to build it from source.

[simonai1254]

I am on your side that there should be a new build to enable .net 5 by default. For now to get it working you do not need to rebuild it (even thouugh you may), but the easiest way is to just adapt the file "Unosquare.PassCore.Web.runtimeconfig.json" as described in issue #615.

[unquietwiki]

https://devblogs.microsoft.com/dotnet/announcing-net-6/

.NET 6 is out; I've updated the issue to reflect that.

[geoperez]

Check the latest commit.

[unquietwiki]

Adding note regarding existence of #668