Compiling GoSteamLanguageGenerator.csproj fails

[Nuc1eoN]

I am trying to compile GoSteamLanguageGenerator.csproj according to the appended readme, but getting the following error:

$ xbuild GoSteamLanguageGenerator.csproj /p:OutputPath=bin/Debug

>>>> xbuild tool is deprecated and will be removed in future updates, use msbuild instead <<<<

XBuild Engine Version 14.0
Mono, Version 5.20.1.0
Copyright (C) 2005-2013 Various Mono authors

Build started 07/30/2019 13:50:29.
__________________________________________________
Project "/home/nuc/go/src/github.com/faceit/go-steam/generator/GoSteamLanguageGenerator/GoSteamLanguageGenerator.csproj" (default target(s)):
        Target PrepareForBuild:
                Configuration: Debug Platform: x86
        Target ResolveProjectReferences:
/home/nuc/go/src/github.com/faceit/go-steam/generator/SteamKit/Resources/SteamLanguageParser/SteamLanguageParser.csproj: error : /home/nuc/go/src/github.com/faceit/go-steam/generator/SteamKit/Resources/SteamLanguageParser/SteamLanguageParser.csproj: The default XML namespace of the project must be the MSBuild XML namespace. If the project is authored in the MSBuild 2003 format, please add xmlns="http://schemas.microsoft.com/developer/msbuild/2003" to the <Project> element. If the project has been authored in the old 1.0 or 1.2 format, please convert it to MSBuild 2003 format.  
        Task "MSBuild" execution -- FAILED
        Done building target "ResolveProjectReferences" in project "/home/nuc/go/src/github.com/faceit/go-steam/generator/GoSteamLanguageGenerator/GoSteamLanguageGenerator.csproj".-- FAILED
Done building project "/home/nuc/go/src/github.com/faceit/go-steam/generator/GoSteamLanguageGenerator/GoSteamLanguageGenerator.csproj".-- FAILED

Build FAILED.
Errors:

/home/nuc/go/src/github.com/faceit/go-steam/generator/GoSteamLanguageGenerator/GoSteamLanguageGenerator.csproj (default targets) ->
/usr/lib/mono/xbuild/14.0/bin/Microsoft.Common.targets (ResolveProjectReferences target) ->

        /home/nuc/go/src/github.com/faceit/go-steam/generator/SteamKit/Resources/SteamLanguageParser/SteamLanguageParser.csproj: error : /home/nuc/go/src/github.com/faceit/go-steam/generator/SteamKit/Resources/SteamLanguageParser/SteamLanguageParser.csproj: The default XML namespace of the project must be the MSBuild XML namespace. If the project is authored in the MSBuild 2003 format, please add xmlns="http://schemas.microsoft.com/developer/msbuild/2003" to the <Project> element. If the project has been authored in the old 1.0 or 1.2 format, please convert it to MSBuild 2003 format.  

         0 Warning(s)
         1 Error(s)

Time Elapsed 00:00:00.2284670

I have also tried the newer msbuild tool:

$ msbuild GoSteamLanguageGenerator.csproj /p:OutputPath=bin/Debug
Microsoft (R) Build Engine version 16.0.0.0 for Mono
Copyright (C) Microsoft Corporation. All rights reserved.

Build started 07/30/2019 13:50:37.
Project "/home/nuc/go/src/github.com/faceit/go-steam/generator/GoSteamLanguageGenerator/GoSteamLanguageGenerator.csproj" on node 1 (default targets).
/usr/lib/mono/msbuild/15.0/bin/Microsoft.Common.CurrentVersion.targets(1677,5): error : Project '../SteamKit/Resources/SteamLanguageParser/SteamLanguageParser.csproj' targets 'netcoreapp2.0'. It cannot be referenced by a project that targets '.NETFramework,Version=v4.0'. [/home/nuc/go/src/github.com/faceit/go-steam/generator/GoSteamLanguageGenerator/GoSteamLanguageGenerator.csproj]
Done Building Project "/home/nuc/go/src/github.com/faceit/go-steam/generator/GoSteamLanguageGenerator/GoSteamLanguageGenerator.csproj" (default targets) -- FAILED.

Build FAILED.

"/home/nuc/go/src/github.com/faceit/go-steam/generator/GoSteamLanguageGenerator/GoSteamLanguageGenerator.csproj" (default target) (1) ->
(_GetProjectReferenceTargetFrameworkProperties target) -> 
  /usr/lib/mono/msbuild/15.0/bin/Microsoft.Common.CurrentVersion.targets(1677,5): error : Project '../SteamKit/Resources/SteamLanguageParser/SteamLanguageParser.csproj' targets 'netcoreapp2.0'. It cannot be referenced by a project that targets '.NETFramework,Version=v4.0'. [/home/nuc/go/src/github.com/faceit/go-steam/generator/GoSteamLanguageGenerator/GoSteamLanguageGenerator.csproj]

    0 Warning(s)
    1 Error(s)

Time Elapsed 00:00:01.00

[Nuc1eoN]

Fixed upstream.