[format.syn] Add \libconcept for input_range (#7443)

Author: hewillk

source/text.tex

@@ -5890,7 +5890,7 @@
              @\libconcept{formattable}@<ranges::range_reference_t<R>, charT>
   struct formatter<R, charT> : @\exposid{range-default-formatter}@<format_kind<R>, R, charT> { };
 
-  template<ranges::input_range R>
+  template<ranges::@\libconcept{input_range}@ R>
       requires (format_kind<R> != range_format::disabled)
     constexpr bool enable_nonlocking_formatter_optimization<R> = false;