Minimum/maximum supported dotnet version for sharp

I have found that sharp builds successfully on dotnet 5.0, which is EOL. On 6.0, the current LTS, the build fails with the following errors:
```
> /build/source/sharp/Olympus.Sharp.csproj : error NU1102: Unable to find package Microsoft.NETFramework.ReferenceAssemblies with version (>= 1.0.2)
> /build/source/sharp/Olympus.Sharp.csproj : error NU1102: - Found 1 version(s) in nugetSource [ Nearest version: 1.0.0 ]
```
I'm not that much of a dotnet person, but the csproj mentions requiring `net452`, which I assume is dotnet 4.5.2. Is this the current state of affairs or am I just doing something wrong? I had to put in some extra work to support 5.0 as it is EOL and has been removed from nixpkgs.