feat: fix deprecation

Author: Chris8934

Diff for: phpstan-baseline.neon

@@ -60,11 +60,6 @@ parameters:
 			count: 1
 			path: src/Cookie.php
 
-		-
-			message: "#^Parameter \\#1 \\$string of function rtrim expects string, string\\|null given\\.$#"
-			count: 1
-			path: src/Cookie.php
-
 		-
 			message: "#^Class Http\\\\Message\\\\CookieJar implements generic interface IteratorAggregate but does not specify its types\\: TKey, TValue$#"
 			count: 1