fix php 7.2

Author: staabm

src/Rules/Regexp/RegularExpressionPatternRule.php

@@ -128,7 +128,7 @@ private function validatePattern(string $pattern): ?string
 		try {
 			Strings::match('', $pattern);
 		} catch (RegexpException $e) {
-			if (str_contains($e->getMessage(), 'UTF-8 error')) {
+			if (str_contains($e->getMessage(), 'Compilation failed') && str_contains($e->getMessage(), 'UTF-8')) {
 				$patternPos = strpos($e->getMessage(), 'pattern:');
 				if ($patternPos === false) {
 					throw new ShouldNotHappenException();