diff: Avoid Phan warning with some Wikidiff2 versions

Something changed in WMF CI config that causes this warning to be
emitted, perhaps T397429#11035011.

Change-Id: Ib477c1812c48a96b252a4f687e09f1ca5c30c2f3
(cherry picked from commit 4b5fc06c5e34b0a9332c9228ac3c28fd0f750c6c)

includes/diff/TextDiffer/Wikidiff2TextDiffer.php

@@ -151,6 +151,7 @@ class Wikidiff2TextDiffer extends BaseTextDiffer {
 	 * @param string $old
 	 * @param string $new
 	 * @return string
+	 * @suppress PhanParamTooManyInternal,UnusedSuppression Spurious Phan warning with wikidiff <1.5.0 or >=1.8.0
 	 */
 	private function doTableFormat( $old, $new ) {
 		if ( $this->haveCutoffParameter ) {