External Libraries: Update getID3() to 1.9.19.

Changelog: https://github.com/JamesHeinrich/getID3/compare/v1.9.18...v1.9.19

Props ayeshrajans, schlessera.
See #49945.

git-svn-id: https://develop.svn.wordpress.org/trunk@47601 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/ID3/module.audio.ac3.php

@@ -485,7 +485,7 @@ class getid3_ac3 extends getid3_handler
 	/**
 	 * @param int $length
 	 *
-	 * @return float|int
+	 * @return int
 	 */
 	private function readHeaderBSI($length) {
 		$data = substr($this->AC3header['bsi'], $this->BSIoffset, $length);