<6 upper bound to celery dependency (#75)

* Remove upper bound to `celery` dependency

* `<6` upper bound for `celery`

Author: Viicos

setup.py

@@ -4,7 +4,7 @@
 
 
 INSTALL_REQUIRES = [
-    'celery>=5.0,<5.3',
+    'celery>=5.0,<6',
     'mail-parser',
     'pytz',
 ]