Normalize WINDIR path for bundled DLLs in CMake

Replaces backslashes with forward slashes in the WINDIR environment variable and updates DLL paths to use the normalized variable. This ensures consistent path formatting for bundled system libraries.

Author: FeodorFitsner

src/serious_python_windows/windows/CMakeLists.txt

@@ -69,12 +69,13 @@ target_link_libraries(${PLUGIN_NAME} PRIVATE
 # List of absolute paths to libraries that should be bundled with the plugin.
 # This list could contain prebuilt libraries, or libraries created by an
 # external build triggered from this build file.
+string(REPLACE "\\" "/" SERIOUS_PYTHON_WINDIR "$ENV{WINDIR}")
 set(serious_python_windows_bundled_libraries
   "${PYTHON_PACKAGE}/python312$<$<CONFIG:Debug>:_d>.dll"
   "${PYTHON_PACKAGE}/python3$<$<CONFIG:Debug>:_d>.dll"
-  "$ENV{WINDIR}/system32/msvcp140.dll"
-  "$ENV{WINDIR}/system32/vcruntime140.dll"
-  "$ENV{WINDIR}/system32/vcruntime140_1.dll"
+  "${SERIOUS_PYTHON_WINDIR}/System32/msvcp140.dll"
+  "${SERIOUS_PYTHON_WINDIR}/System32/vcruntime140.dll"
+  "${SERIOUS_PYTHON_WINDIR}/System32/vcruntime140_1.dll"
   PARENT_SCOPE
 )