Remove reference to Django core team

[bmispelon]

While reviewing #1672 I noticed that there was a page still referencing the Django core team:

djangoproject.com/djangoproject/templates/conduct/changes.html

Line 18 in d786988

sent to the DSF, the Django core team, and the Django community for comment.

The Django core team was dissolved a while back, so the text of this page and any others (git grep -i "core team" seems to yield other files too) should be updated.