Editing a message doesn't trigger a re-render on the other user's screen

[adamshapiro0]

When you edit the math in a message, it rerenders correctly on your own screen. On the other user's screen, however, the rendered math stays the same even though the slack message gets marked as (edited).

To reproduce:

1. Send some math (e.g., $e = mc^2$)
2. Edit the message and modify the math (e.g., $e = mc^3$)
3. The message will be tagged as (edited) and the new math should appear on your screen, but not on recipient's

If the recipient restarts Slack, the edited message does get rerendered correctly.