[libc++] Fixes the CI.

The GDB test was disabled for clang-15, updated the filter since main
now is clang-16.

Author: mordante

libcxx/test/libcxx/gdb/gdb_pretty_printer_test.sh.cpp

@@ -12,7 +12,7 @@
 // UNSUPPORTED: c++03
 
 // TODO: Investigate this failure, which happens only with the Bootstrapping build.
-// UNSUPPORTED: clang-13, clang-14, clang-15
+// UNSUPPORTED: clang-13, clang-14, clang-15, clang-16
 
 // TODO: Investigate this failure on GCC 12 (in Ubuntu Jammy)
 // UNSUPPORTED: gcc-12