Enforce C++20 standard for plugin build

Added target_compile_features to require C++20 for the plugin. This ensures the code is compiled with C++20 features and compatibility.

Author: FeodorFitsner

src/serious_python_windows/windows/CMakeLists.txt

@@ -42,6 +42,7 @@ add_library(${PLUGIN_NAME} SHARED
 # application-level CMakeLists.txt. This can be removed for plugins that want
 # full control over build settings.
 apply_standard_settings(${PLUGIN_NAME})
+target_compile_features(${PLUGIN_NAME} PRIVATE cxx_std_20)
 
 # Symbols are hidden by default to reduce the chance of accidental conflicts
 # between plugins. This should not be removed; any symbols that should be
@@ -105,4 +106,4 @@ if(DEFINED ENV{SERIOUS_PYTHON_SITE_PACKAGES})
       "$ENV{SERIOUS_PYTHON_SITE_PACKAGES}"
       "${CMAKE_BINARY_DIR}/runner/$<$<CONFIG:Release>:Release>$<$<CONFIG:Debug>:Debug>/site-packages"
   )
-endif()
+endif()