Delete from the cache on Get if the item expired (to trigger onEvicted)

cache.go

@@ -128,6 +128,7 @@ func (c *cache) Get(k string) (interface{}, bool) {
 	if item.Expiration > 0 {
 		if time.Now().UnixNano() > item.Expiration {
 			c.mu.RUnlock()
+			c.Delete(k)
 			return nil, false
 		}
 	}