Pick a more commonplace escape char for the test

The Mysql family does not seem to like that one.

tests/Doctrine/Tests/DBAL/Functional/LikeWildcardsEscapingTest.php

@@ -9,7 +9,7 @@ final class LikeWildcardsEscapingTest extends DbalFunctionalTestCase
     public function testFetchLikeExpressionResult() : void
     {
         $string = '_25% off_ your next purchase \o/';
-        $escapeChar = '£';
+        $escapeChar = '!';
         $stmt = $this->_conn->prepare(sprintf(
             "SELECT '%s' LIKE '%s' ESCAPE '%s' as it_matches",
             $string,