Remove unneeded typename from test

[chill]

FYI, there is a similar issue in test/std/utilities/variant/variant.helpers/variant_alternative.fail.cpp added by the
same commit

git hash: a12318f5ae0aae44eb17f376d3598717b45f7a5f
"Added failing tests for index out of range for tuple_element<pair<T1,T2>> and variant_alternative<>"

[rogfer01]

• Remove another instance of this issue

[rogfer01]

Thanks @chill , @mclow.lists and @EricWF !

test/std/utilities/utility/pairs/pair.astuple/tuple_element.fail.cpp

 
 // tuple_element<I, pair<T1, T2> >::type
 
 #include <utility>
 
 int main()
 {
     typedef std::pair<int, short> T;
-    typename std::tuple_element<2, T>::type foo; // expected-error@utility:* {{Index out of bounds in std::tuple_element<std::pair<T1, T2>>}}
+    std::tuple_element<2, T>::type foo; // expected-error@utility:* {{Index out of bounds in std::tuple_element<std::pair<T1, T2>>}}
 }