Fix the pattern

The Pattern was not the correct one fixing it by the pattern of RFC3339

types.go

@@ -19,5 +19,5 @@ type Timestamp string
 // Parse parses a timestamp string into a time.Time object.
 // The only time this can fail is if Discord changes their timestamp format.
 func (t Timestamp) Parse() (time.Time, error) {
-	return time.Parse("2006-01-02T15:04:05.000000-07:00", string(t))
+	return time.Parse(time.RFC3339, string(t))
 }