[Feat] .Net 6 support

[pgrm]

Describe the solution you'd like

Add support for .Net 6 so it works without warnings

Currently when using this package with .Net 6 I get the following warning:

resource BlazorTable.xml in BlazorTable, Version=1.17.0.0, Culture=neutral, PublicKeyToken=null(13,6): warning IL2008: Could not resolve type 'System.Threading.WasmRuntime' 

I can ignore the warning and it seems to work just fine, however, AFAIK I can only ignore the complete IL2008 warning and not a specific one, so in case I have a wrong configuration in my own linker config, I wouldn't get any warning / error.

To reproduce this behaviour check https://github.com/pgrm/BlazorTableDotnet6Support