fix: MP_UNITS_BUILD_IMPORT_STD verification fixed

Author: mpusz

src/CMakeLists.txt

@@ -126,12 +126,12 @@ else()
     set(${projectPrefix}TARGET_SCOPE "INTERFACE")
 endif()
 
-if(${projectPrefix}BUILD_CXX_MODULES)
+if(${projectPrefix}BUILD_IMPORT_STD)
     if(CMAKE_VERSION VERSION_LESS "3.30")
         message(FATAL_ERROR "CMake versions before 3.30 do not support `import std;` properly")
     endif()
     if(CMAKE_CXX_STANDARD LESS 23)
-        message(FATAL_ERROR "`import std;` requires at lease C++23")
+        message(FATAL_ERROR "`import std;` requires at least C++23")
     endif()
 endif()