Update RegularExpressionPatternRule.php

Author: staabm

Diff for: src/Rules/Regexp/RegularExpressionPatternRule.php

@@ -15,6 +15,7 @@
 use function sprintf;
 use function str_contains;
 use function str_starts_with;
+use function strlen;
 use function strpos;
 use function strtolower;
 use function substr;