gh-126499: test_ssl: Don't assume err.reason is a string (GH-126501)

The skipping machinery called `getattr(err, "reason", "")` on an arbitrary
exception. As intermittent Buildbot failures show, sometimes it's set
to None.

Convert it to string for this specific check.

Author: encukou

Lib/test/test_ssl.py

@@ -5029,7 +5029,7 @@ def non_linux_skip_if_other_okay_error(self, err):
             return  # Expect the full test setup to always work on Linux.
         if (isinstance(err, ConnectionResetError) or
             (isinstance(err, OSError) and err.errno == errno.EINVAL) or
-            re.search('wrong.version.number', getattr(err, "reason", ""), re.I)):
+            re.search('wrong.version.number', str(getattr(err, "reason", "")), re.I)):
             # On Windows the TCP RST leads to a ConnectionResetError
             # (ECONNRESET) which Linux doesn't appear to surface to userspace.
             # If wrap_socket() winds up on the "if connected:" path and doing