Remove useless code

Author: alexandre-daubois

RouteCompiler.php

@@ -154,7 +154,7 @@ private static function compilePattern(Route $route, string $pattern, bool $isHo
 
             $regexp = $route->getRequirement($varName);
             if (null === $regexp) {
-                $followingPattern = (string) substr($pattern, $pos);
+                $followingPattern = substr($pattern, $pos);
                 // Find the next static character after the variable that functions as a separator. By default, this separator and '/'
                 // are disallowed for the variable. This default requirement makes sure that optional variables can be matched at all
                 // and that the generating-matching-combination of URLs unambiguous, i.e. the params used for generating the URL are