[3.13] Skip test in test_socket.py if sys.getrefcount isn't availab…

…le (pythonGH-126640) (python#126645)

Skip test in test_socket.py if `sys.getrefcount` isn't available (pythonGH-126640)

Skip `testMakefileCloseSocketDestroy` test if `sys.getrefcount` isn't available. This is necessary for  PyPy and other Python implementations that do not have `sys.getrefcount`.
(cherry picked from commit 0f6bb28)

Co-authored-by: CF Bolz-Tereick <cfbolz@gmx.de>

Lib/test/test_socket.py

@@ -5328,6 +5328,8 @@ def _testMakefileClose(self):
         self.write_file.write(self.write_msg)
         self.write_file.flush()
 
+    @unittest.skipUnless(hasattr(sys, 'getrefcount'),
+                         'test needs sys.getrefcount()')
     def testMakefileCloseSocketDestroy(self):
         refcount_before = sys.getrefcount(self.cli_conn)
         self.read_file.close()