bpo-41473: Skip test_gdb with gdb 9.2 to work around gdb bug (GH-21768)

gdb 9.2 on Fedora Rawhide is not reliable, see:

* https://bugs.python.org/issue41473
* https://bugzilla.redhat.com/show_bug.cgi?id=1866884
diff --git a/Lib/test/test_gdb.py b/Lib/test/test_gdb.py
index 22c75ba..44cb9a0 100644
--- a/Lib/test/test_gdb.py
+++ b/Lib/test/test_gdb.py
@@ -51,6 +51,11 @@
                             "embedding. Saw %s.%s:\n%s"
                             % (gdb_major_version, gdb_minor_version,
                                gdb_version))
+if (gdb_major_version, gdb_minor_version) >= (9, 2):
+    # gdb 9.2 on Fedora Rawhide is not reliable, see:
+    # * https://bugs.python.org/issue41473
+    # * https://bugzilla.redhat.com/show_bug.cgi?id=1866884
+    raise unittest.SkipTest("https://bugzilla.redhat.com/show_bug.cgi?id=1866884")
 
 if not sysconfig.is_python_build():
     raise unittest.SkipTest("test_gdb only works on source builds at the moment.")