reko docker image no longer builds

[edmcman]

It seems like reko master requires .NET 8.0 now:

 > [reko reko 3/4] RUN git clone --depth=1 https://github.com/uxmal/reko.git     && cd reko     && dotnet msbuild -p:Platform=x64 -p:Configuration=UnixRelease -t:build_solution -m ./src/BuildTargets/BuildTargets.csproj     && dotnet msbuild -p:Platform=x64 -p:Configuration=Release -t:create_runtime_nupkg -m ./src/BuildTargets/BuildTargets.csproj     && dotnet msbuild -p:Platform=x64 -p:Configuration=Release -t:create_release -m ./src/BuildTargets/BuildTargets.csproj     && cp bin/CmdLine*.zip ../CmdLine.zip     && cd ..     && rm -rf reko .nuget:
0.232 Cloning into 'reko'...
23.69 
23.69 Welcome to .NET 6.0!
23.69 ---------------------
23.69 SDK Version: 6.0.428
23.69 
23.69 Telemetry
23.69 ---------
23.69 The .NET tools collect usage data in order to help us improve your experience. It is collected by Microsoft and shared with the community. You can opt-out of telemetry by setting the DOTNET_CLI_TELEMETRY_OPTOUT environment variable to '1' or 'true' using your favorite shell.
23.69 
23.69 Read more about .NET CLI Tools telemetry: https://aka.ms/dotnet-cli-telemetry
23.69 
23.69 ----------------
23.69 Installed an ASP.NET Core HTTPS development certificate.
23.69 To trust the certificate run 'dotnet dev-certs https --trust' (Windows and macOS only).
23.69 Learn about HTTPS: https://aka.ms/dotnet-https
23.69 ----------------
23.69 Write your first app: https://aka.ms/dotnet-hello-world
23.69 Find out what's new: https://aka.ms/dotnet-whats-new
23.69 Explore documentation: https://aka.ms/dotnet-docs
23.69 Report issues and find source on GitHub: https://github.com/dotnet/core
23.69 Use 'dotnet --help' to see available commands or visit: https://aka.ms/dotnet-cli
23.69 --------------------------------------------------------------------------------------
23.91 MSBuild version 17.3.4+a400405ba for .NET
24.10   -- CMake args: /home/decompiler_user/reko/cmake/../src/../;-DCMAKE_BUILD_TYPE=UnixRelease;-DREKO_SRC=/home/decompiler_user/reko/cmake/../src;-DREKO_PLATFORM=x64;-DTARGET=build_solution
24.10   == Configuration ==
24.10   => Build Type: UnixRelease
24.10   => Generator : 
24.10   => Platform  : x64
24.10   => Target    : build_solution
24.10   
24.15   -- Found .NET toolchain: /usr/bin/dotnet (version 6.0.428)
24.16   -- Configuring done
24.17   -- Generating done
24.17   -- Build files have been written to: /home/decompiler_user/reko/src/BuildTargets/build/build_solution
24.17   -- Build Args: --target;build_solution
24.21   [100%] Building solution...
24.29   MSBuild version 17.3.4+a400405ba for .NET
25.19     Determining projects to restore...
25.68 /usr/share/dotnet/sdk/6.0.428/Sdks/Microsoft.NET.Sdk/targets/Microsoft.NET.TargetFrameworkInference.targets(144,5): error NETSDK1045: The current .NET SDK does not support targeting .NET 8.0.  Either target .NET 6.0 or lower, or use a version of the .NET SDK that supports .NET 8.0. [/home/decompiler_user/reko/src/Arch/Sparc/Sparc.csproj] [/home/decompiler_user/reko/src/BuildTargets/BuildTargets.csproj]
25.68 /usr/share/dotnet/sdk/6.0.428/Sdks/Microsoft.NET.Sdk/targets/Microsoft.NET.TargetFrameworkInference.targets(144,5): error NETSDK1045: The current .NET SDK does not support targeting .NET 8.0.  Either target .NET 6.0 or lower, or use a version of the .NET SDK that supports .NET 8.0. [/home/decompiler_user/reko/src/Decompiler/Decompiler.csproj] [/home/decompiler_user/reko/src/BuildTargets/BuildTargets.csproj]