Revert "Returns SMF\TimeInterval objects from SMF\Time::diff()"

This reverts commit 2841c29.

Sources/Time.php

@@ -439,18 +439,6 @@ public function __isset(string $prop): bool
 		}
 	}
 
-	/**
-	 * Like \DateTime::diff(), but returns a TimeInterval object.
-	 *
-	 * @param \DateTimeInterface $target The date to compare to.
-	 * @param bool $absolute Whether to force the interval to be positive.
-	 * @return TimeInterval The difference between the two dates.
-	 */
-	public function diff(\DateTimeInterface $target, bool $absolute = false): TimeInterval
-	{
-		return TimeInterval::createFromDateInterval(parent::diff($target, $absolute));
-	}
-
 	/**
 	 * Like DateTime::format(), except that it can accept either DateTime format
 	 * specifiers or strftime format specifiers (but not both at once).