Fix DotNetVersion parse order (#6180)

[michaelmccord]

The errors noted in #6180 are due to a race condition between the evaluation of the property and the execution of the dotnet --version command.

Closes #6180

[CLAassistant]

All committers have signed the CLA.

[michaelstaib]

Thank you for your help!

[michaelmccord]

Thank you for your help!

@michaelstaib No problem. Can this get backed merged into the 13.1.x line?

[michaelstaib]

Yes ... there is already a preview build... or there will be in 15 min

[michaelmccord]

Yes ... there is already a preview build... or there will be in 15 min

Awesome. Thanks!

[huysentruitw]

Is there a reason for not using $(TargetFrameworkVersion) instead of generating a DotNetVersion using the cli?

F.e:

    <PropertyGroup>
      <DotNetMajor Condition="$([MSBuild]::VersionGreaterThanOrEquals($(TargetFrameworkVersion), 6))">6</DotNetMajor>
      <DotNetMajor Condition="$([MSBuild]::VersionGreaterThanOrEquals($(TargetFrameworkVersion), 7))">7</DotNetMajor>
    </PropertyGroup>