Prevent long extension descriptions from overflowing (#9348)

This PR fixes an issue where long extension descriptions could take up
more room than intended, pushing the GitHub repository icon off the
screen.

<img width="901" alt="Screenshot 2024-03-14 at 12 54 14 PM"
src="https://github.com/zed-industries/zed/assets/1486634/befce468-f8df-4183-b3cc-9d088dd53b4e">

Fixes #9331.

Release Notes:

- Fixed an issue where long extension descriptions could push the GitHub
repository icon off the screen
([#9331](https://github.com/zed-industries/zed/issues/9331)).