Fix linux for ninja and dotnet checkups

[ramezgerges]

No description provided.

[ramezgerges]

@jeromelaban I came around to this PR and finally found the problem. We were using the pre-existing dotnet installation (net3.0 in CI I think) instead of the newly installed version (net8) to search for and install the templates. Linux and macOS are now passing, but Windows is giving me

Failed to load the dll from [C:\Program Files (x86)\dotnet\host\fxr\8.0.1\hostfxr.dll], HRESULT: 0x800700C1
The library hostfxr.dll was found, but loading it from C:\Program Files (x86)\dotnet\host\fxr\8.0.1\hostfxr.dll failed
  - Installing .NET prerequisites might help resolve this problem.
     https://go.microsoft.com/fwlink/?linkid=798306

It's highly unlikely that this PR had something to do with that, so could you take a look? Might this be about CI's windows version being below the minimum needed for net8?

[jeromelaban]

@ramezgerges it's likely that this PR is causing this issue, as the very recent PRs from two days ago don't have this issue. We'll have to look again at the code executed for the .NET installation on windows.