Bump version to 2.9.3

Fix unconverted PRs in the changelog (mastodon#11155)

Bump version to 2.9.1 (mastodon#11143)

Bump version to 2.9.0 (mastodon#11074)

Bump version to 2.9.0rc2 (mastodon#11070)

Bump version to 2.9.0rc1 (mastodon#11004)

Bump version to 2.8.4

Bump version to 2.8.3

Bump version to 2.8.2 (mastodon#10703)

Add `tootctl cache clear` (mastodon#10689)