Fix test_gdb following the small unicode struct change in c25262e97304 (issue #13130)
diff --git a/Tools/gdb/libpython.py b/Tools/gdb/libpython.py
index 4b42c8b..43a0f20 100644
--- a/Tools/gdb/libpython.py
+++ b/Tools/gdb/libpython.py
@@ -1152,7 +1152,7 @@
                     field_str = field_str.cast(_type_unsigned_char_ptr)
                 elif repr_kind == 2:
                     field_str = field_str.cast(_type_unsigned_short_ptr)
-                elif repr_kind == 3:
+                elif repr_kind == 4:
                     field_str = field_str.cast(_type_unsigned_int_ptr)
         else:
             # Python 3.2 and earlier