[temp.constr.normal] Add missing semicolon in example (#5395)

Author: Dani-Hub

source/templates.tex

@@ -1897,7 +1897,7 @@
 template<typename T> concept C1 = sizeof(T) == 1;
 template<typename T> concept C2 = C1<T> && 1 == 2;
 template<typename T> concept C3 = requires { typename T::type; };
-template<typename T> concept C4 = requires (T x) { ++x; }
+template<typename T> concept C4 = requires (T x) { ++x; };
 
 template<C2 U> void f1(U);      // \#1
 template<C3 U> void f2(U);      // \#2