Use PlatformToolSet v145 by default when building with VS 2026

Furthermore, do not warn anymore when building with v145

Author: chris-eibl

PCbuild/python.props

@@ -11,7 +11,7 @@
 
     We set BasePlatformToolset for ICC's benefit, it's otherwise ignored.
     -->
-    <BasePlatformToolset Condition="'$(BasePlatformToolset)' == '' and '$(VisualStudioVersion)' == '18.0'">v143</BasePlatformToolset>
+    <BasePlatformToolset Condition="'$(BasePlatformToolset)' == '' and '$(VisualStudioVersion)' == '18.0'">v145</BasePlatformToolset>
     <BasePlatformToolset Condition="'$(BasePlatformToolset)' == '' and '$(VisualStudioVersion)' == '17.0'">v143</BasePlatformToolset>
     <BasePlatformToolset Condition="'$(BasePlatformToolset)' == '' and '$(VisualStudioVersion)' == '16.0'">v142</BasePlatformToolset>
     <BasePlatformToolset Condition="'$(BasePlatformToolset)' == '' and ('$(MSBuildToolsVersion)' == '15.0' or '$(VisualStudioVersion)' == '15.0')">v141</BasePlatformToolset>

PCbuild/pythoncore.vcxproj

@@ -728,7 +728,7 @@
       </ClCompile>
     </ItemGroup>
   </Target>
-  <Target Name="_WarnAboutToolset" BeforeTargets="PrepareForBuild" Condition="$(PlatformToolset) != 'v141' and $(PlatformToolset) != 'v142' and $(PlatformToolset) != 'v143'">
+  <Target Name="_WarnAboutToolset" BeforeTargets="PrepareForBuild" Condition="$(PlatformToolset) != 'v141' and $(PlatformToolset) != 'v142' and $(PlatformToolset) != 'v143' and $(PlatformToolset) != 'v145'">
     <Warning Text="Toolset $(PlatformToolset) is not used for official builds. Your build may have errors or incompatibilities." />
   </Target>
   <Target Name="_WarnAboutZlib" BeforeTargets="PrepareForBuild" Condition="!$(IncludeExternals)">