Bump heroku to 3.99.1
Bump heroku to 3.99.1

Bumps [heroku](https://github.com/heroku/heroku) from 3.41.5 to 3.99.1.
- [Commits](https://github.com/heroku/heroku/commits)

If you'd like to skip this version, you can just close this PR. If you have any feedback just mention @dependabot in the comments below.
samjewell/silverspoon,samjewell/silverspoon,samjewell/silverspoon