pythongh-131339: test PyBytes_Size for a zero-size bytes object (python#131340)

Author: nybblista

Lib/test/test_capi/test_bytes.py

@@ -93,6 +93,7 @@ def test_size(self):
         # Test PyBytes_Size()
         size = _testlimitedcapi.bytes_size
 
+        self.assertEqual(size(b''), 0)
         self.assertEqual(size(b'abc'), 3)
         self.assertEqual(size(BytesSubclass(b'abc')), 3)
         self.assertRaises(TypeError, size, bytearray(b'abc'))