Unable to specify prerelease versions of Visual Studio

[MarkIngramUK]

microsoft/setup-msbuild allows the following input:

    - name: Add MSBuild to PATH
      uses: microsoft/[email protected]
      with:
        vs-prerelease: true

Which adds the -prerelease flag to the command line to vswhere:

vswhere.exe -products * -requires Microsoft.Component.MSBuild -property installationPath -latest -prerelease

This allows setup-msbuild to work with the windows-2022 runner which ships with Visual Studio 2022 Preview installed. Without the -prerelease flag, vswhere will not find MSBuild / VSTest.