Update warning message to allow v141.

Author: zooba

PCbuild/pythoncore.vcxproj

@@ -429,7 +429,7 @@
  </ClCompile>
  </ItemGroup>
  </Target>
- <Target Name="_WarnAboutToolset" BeforeTargets="PrepareForBuild" Condition="$(PlatformToolset) != 'v140'">
+ <Target Name="_WarnAboutToolset" BeforeTargets="PrepareForBuild" Condition="$(PlatformToolset) != 'v140' and $(PlatformToolset) != 'v141'">
  <Warning Text="Toolset $(PlatformToolset) is not used for official builds. Your build may have errors or incompatibilities." />
  </Target>
 </Project>