[tuple.tuple] Remove extra space before class scope (#1846)

Author: JohelEGP

source/utilities.tex

@@ -1087,7 +1087,7 @@
 \begin{codeblock}
 namespace std {
   template <class... Types>
-    class tuple  {
+    class tuple {
     public:
       // \ref{tuple.cnstr}, \tcode{tuple} construction
       @\EXPLICIT@ constexpr tuple();