[kemonoparty] fix 'username' extraction (fixes #1652)

The site's <title> content changed from

<title>NAME | Kemono</title>

to

<title>
    NAME | Kemono
</title>

test/test_results.py

@@ -315,6 +315,9 @@ def setup_test_config():
                      "e621", "inkbunny", "tapas", "pillowfort", "mangadex"):
         config.set(("extractor", category), "username", None)
 
+    config.set(("extractor", "kemonoparty"), "cookies", {
+        "__ddg1": "0gBDGpJ3KZQmA4B9QH25", "__ddg2": "lmj5s1jnJOvhPXCX"})
+
     config.set(("extractor", "mastodon.social"), "access-token",
                "Blf9gVqG7GytDTfVMiyYQjwVMQaNACgf3Ds3IxxVDUQ")