Add Mattermost 7.0 changelog

• Review link

added Progress::4_Can review label

requested review from @hueser93

assigned to @frust45

changed the description

added Progress::5_Under review label and removed Progress::4_Can review label

added Progress::6_Can merge label and removed Progress::5_Under review label

Dear Tobias @frust45, thanks for preparing this changelog entry. I'll approve and merge this merge request now.

approved this merge request

merged

mentioned in commit 44ea091e