Ignore wider set of files with Psalm

The `tests` subfolder may apparently not be present unless PHPUnit was run before.

Author: XedinUnknown

psalm.xml.dist

@@ -32,7 +32,7 @@
 
     <extraFiles>
         <ignoreFiles>
-            <directory name="vendor/phpunit/php-code-coverage/tests"/>
+            <directory name="vendor/phpunit/php-code-coverage"/>
             <directory name="vendor/phpspec/prophecy"/>
         </ignoreFiles>
         <directory name="vendor" />