Merge branch 'issue/2069' into 'develop'

[#2069] unread_conversation_count

See merge request pleroma/pleroma!2939

diff --cc lib/pleroma/user.ex
Simple merge

diff --cc lib/pleroma/web/mastodon_api/views/account_view.ex
Simple merge

diff --cc test/pleroma/conversation/participation_test.exs
Simple merge

diff --cc test/pleroma/web/mastodon_api/controllers/conversation_controller_test.exs
Simple merge

diff --cc test/pleroma/web/pleroma_api/controllers/conversation_controller_test.exs
Simple merge