remove /arch:AVX for blake2module.c again

I've previously gotten compile errors from clang, because the needed
intrinsics were not available without that option.

Cannot reproduce anymore. Most probably, because I've upgraded to
Visual Studio 17.13.0 Preview 5.0, which now ships with clang 19.1.1
instead of 18.1.8 and they've done that for compatibility with MSVC?

Anyway, let's keep the PR small :)

Author: chris-eibl

PCbuild/pythoncore.vcxproj

@@ -420,7 +420,6 @@
     <ClCompile Include="..\Modules\blake2module.c">
       <PreprocessorDefinitions Condition="'$(Platform)' == 'x64'">HACL_CAN_COMPILE_SIMD128;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <PreprocessorDefinitions Condition="'$(Platform)' == 'x64'">HACL_CAN_COMPILE_SIMD256;%(PreprocessorDefinitions)</PreprocessorDefinitions>
-      <AdditionalOptions>/arch:AVX</AdditionalOptions>
     </ClCompile>
     <ClCompile Include="..\Modules\_codecsmodule.c" />
     <ClCompile Include="..\Modules\_collectionsmodule.c" />