[BL] Fix documentation generation for function

With the extra line between the comment and function definition
doxygen attributes the documentation to other entity.

BaseLib/cpp23.h

@@ -25,10 +25,9 @@ namespace BaseLib
  * Implementation from Scott Meyers : Modern effective c++ , Item 10 Scoped
  * enums
  */
-
 template <typename E>
 constexpr auto to_underlying(E e) noexcept
 {
     return static_cast<std::underlying_type_t<E>>(e);
 }
-}  // namespace BaseLib
\ No newline at end of file
+}  // namespace BaseLib