[triggers] not yet fully Python 3, traceback

Versions

• OS: Debian GNU/Linux buster/sid
• GTK+ Version: 3.22.28
• PyGObject Version: 3.26.1
• python-nbxmpp Version: 0.6.3
• Gajim Version: 0.99.2

Traceback

Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/gajim/./data/plugins/triggers/triggers.py", line 587, in on_recipient_list_entry_changed
    recipients = widget.get_text().decode('utf-8')
AttributeError: 'str' object has no attribute 'decode'

Steps to reproduce the problem

1. go to the triggers plugin config
2. select e.g. "When: Receive a Message" and "for: contact(s)"
3. type a character in the entry field
4. traceback!