Fix reference to the class recommended instead of PDOException

lib/Doctrine/DBAL/Driver/PDOException.php

@@ -2,6 +2,8 @@
 
 namespace Doctrine\DBAL\Driver;
 
+use Doctrine\DBAL\Driver\PDO\Exception;
+
 /**
  * @deprecated Use {@link Exception} instead
  *

phpcs.xml.dist

@@ -103,6 +103,7 @@
     <!-- See https://github.com/slevomat/coding-standard/issues/770 -->
     <rule ref="SlevomatCodingStandard.Namespaces.UnusedUses">
         <exclude-pattern>lib/Doctrine/DBAL/Driver/ExceptionConverterDriver.php</exclude-pattern>
+        <exclude-pattern>lib/Doctrine/DBAL/Driver/PDOException.php</exclude-pattern>
     </rule>
 
     <!-- see https://github.com/doctrine/dbal/issues/3377 -->