libstdc++: Fix up pr118196.cc test [PR118196]

The test used #include "<generator>", so FAILed everywhere with
fatal error: <generator>: No such file or directory

2024-12-28  Jakub Jelinek  <jakub@redhat.com>

	PR libstdc++/118196
	* testsuite/24_iterators/range_generators/pr118196.cc: Include
	<generator> rather than "<generator>".

Author: jakubjelinek

libstdc++-v3/testsuite/24_iterators/range_generators/pr118196.cc

@@ -1,5 +1,5 @@
 // { dg-do compile { target c++23 } }
-#include "<generator>"
+#include <generator>
 
 std::generator<int>
 generator();