tests/wipy: Improve robustness of time test.

tests/wipy/time.py

@@ -61,12 +61,12 @@ spot_test(-1072915201,  (1965, 12, 31, 23, 59, 59, 4, 365))
 t1 = time.time()
 time.sleep(2)
 t2 = time.time()
-print(time.ticks_diff(t1, t2) == 2)
+print(abs(time.ticks_diff(t1, t2) -2) <= 1)
 
 t1 = time.ticks_ms()
 time.sleep_ms(50)
 t2 = time.ticks_ms()
-print(time.ticks_diff(t1, t2) == 50)
+print(abs(time.ticks_diff(t1, t2)- 50) <= 1)
 
 t1 = time.ticks_us()
 time.sleep_us(1000)