[optional.comp.with.t] Fix indentation (cplusplus#9023)

Author: Andreas-Krug

source/utilities.tex

@@ -5869,7 +5869,7 @@
 \indexlibrarymember{operator<=>}{optional}%
 \begin{itemdecl}
 template<class T, class U>
-    requires (!@\exposconcept{is-derived-from-optional}@<U>) && @\libconcept{three_way_comparable_with}@<T, U>
+  requires (!@\exposconcept{is-derived-from-optional}@<U>) && @\libconcept{three_way_comparable_with}@<T, U>
   constexpr compare_three_way_result_t<T, U>
     operator<=>(const optional<T>& x, const U& v);
 \end{itemdecl}