remove trailing whitespace in diagnostic

Author: evelez7

clang/include/clang/Basic/DiagnosticParseKinds.td

@@ -889,7 +889,7 @@ def err_requires_expr_in_simple_requirement : Error<
   "before the expression)">;
 def missing_template_arg_list_after_template_kw : Extension<
   "a template argument list is expected after a name prefixed by the template "
-  "keyword">, InGroup<DiagGroup<"missing-template-arg-list-after-template-kw">>, 
+  "keyword">, InGroup<DiagGroup<"missing-template-arg-list-after-template-kw">>,
   DefaultError;
 
 def err_missing_dependent_template_keyword : Error<