Expect either matomo.js or piwik.js in piwik plugin test

Fixes tests.

Change-Id: Ie1e0079b30a59ab1c67605d60845d7b66d202a8a
diff --git a/t/plugin/piwik.t b/t/plugin/piwik.t
index 13667d7..0fd1e89 100644
--- a/t/plugin/piwik.t
+++ b/t/plugin/piwik.t
@@ -37,8 +37,7 @@
 
 $t->app->plugin('Kalamar::Plugin::Piwik');
 
-is($t->app->piwik_tag('as-script'), '<script src="/settings/assets/tracking.js"></script>' .
-     '<script src="https://piwik.korap.ids-mannheim.de/piwik.js" async defer></script>');
+like($t->app->piwik_tag('as-script'), qr!<script src="/settings/assets/tracking.js"></script><script src="https://piwik\.korap\.ids-mannheim\.de/(?:matomo|piwik)\.js" async defer></script>!);
 
 $t->get_ok('/doc/faq')
   ->status_is(200)