This update modifies `Bugout.update_entry_content` to accept tags as part of an entry update.
This means that users no longer have to make 2 separate HTTP requests to update an entry and its tags.
It also adds the `tags_action` parameter which takes values from the `bugout.journal.TagsAction` enumeration.
If `tags_action = TagsAction.merge`, the tags that the user passes to `Bugout.update_entry_content` are merged into the tags on the server. If `tags_action = TagsAction.replace`, they *replace* the tags on the server.