Fix typo and replaced ${PROJECT_NAME} by @PROJECT_NAME@

This was not correctly doing the substitution, but rather it's kept at "${PROJECT_NAME}::${LIBRARY_NAME}". This is a problem when you later do "find_package" from another cmake project.

cmake/Config.cmake.in

@@ -4,6 +4,6 @@ if(NOT TARGET ${PROJECT_NAME}::${LIBRARY_NAME})
     include("${CMAKE_CURRENT_LIST_DIR}/@PROJECT_NAME@Targets.cmake")
 endif()
 
-set(@PROJECT_NAME@_lIBRARIES ${PROJECT_NAME}::${LIBRARY_NAME})
+set(@PROJECT_NAME_UPPERCASE@_LIBRARIES @PROJECT_NAME@::@LIBRARY_NAME@)
 
 check_required_components("@PROJECT_NAME@")