Fix patty_timer_expired()

Fix patty_timer_expired() to only check the tv_sec field for a value <=0
when testing for expiry

src/timer.c

@@ -1,7 +1,7 @@
 #include <patty/timer.h>
 
 int patty_timer_expired(struct timeval *timer) {
-    return (timer->tv_sec <= 0 && timer->tv_usec == 0)? 1: 0;
+    return timer->tv_sec <= 0? 1: 0;
 }
 
 void patty_timer_cancel(struct timeval *timer) {