XEP-0444: Fix emoji detection

the emoji lib just released a major release after 5 years, which breaks
the API. This new code is compatible with both.

slixmpp/plugins/xep_0444/stanza.py

@@ -10,6 +10,8 @@ from typing import Set, Iterable
 from slixmpp.xmlstream import ElementBase
 try:
     from emoji import UNICODE_EMOJI
+    if UNICODE_EMOJI.get('en'):
+        UNICODE_EMOJI = UNICODE_EMOJI['en']
 except ImportError:
     UNICODE_EMOJI = None