[ranges.cartesian.iterator] Fix typo "reference_t" => "range_reference_t" (#5777)

Author: hewillk

source/ranges.tex

@@ -14472,8 +14472,8 @@
     using iterator_concept  = @\seebelow@;
     using value_type = tuple<range_value_t<@\exposid{maybe-const}@<Const, First>>,
       range_value_t<@\exposid{maybe-const}@<Const, Vs>>...>;
-    using reference = tuple<reference_t<@\exposid{maybe-const}@<Const, First>>,
-      reference_t<@\exposid{maybe-const}@<Const, Vs>>...>;
+    using reference = tuple<range_reference_t<@\exposid{maybe-const}@<Const, First>>,
+      range_reference_t<@\exposid{maybe-const}@<Const, Vs>>...>;
     using difference_type = @\seebelow@;
 
     @\exposid{iterator}@() requires @\libconcept{forward_range}@<@\exposid{maybe-const}@<Const, First>> = default;