Relax memory test.

Sometimes used memory shrinks due to GC.

Author: termim

tests/test_memory.py

@@ -24,7 +24,7 @@ def test_memory_leak_on_unsuccessful_connect():
         duss = m1.uss - m0.uss
         print(i, "uss=", m1.uss, "duss:", duss)
         if i > 5:
-            assert duss == 0
+            assert duss <= 0
         m0 = m1