Rename bracket-push exercise

[smuroff]

I had troubles with configlet because bracket-push exercise was renamed (exercism/problem-specifications#1501) . Inspired by #277.

$ configlet generate cpp/
-> 1 error occurred:

* open D:\develop\github\exercism\problem-specifications\exercises\bracket-push\metadata.yml: The system cannot find the path specified.

Closes #277

[arcuru]

Ah, I was hoping to try to get #276 merged first to reduce churn, but if you're getting hit with this it should be fixed. Thanks!

Also FYI, you can auto-close related issues using https://help.github.com/en/articles/closing-issues-using-keywords if you put the message in the first note in the PR :)

This is failing the CI because of the rename. The Rust track hit the same issue, because I based our script off of theirs: exercism/rust#819

Luckily they already found the fix. I'm going to add their fix here myself and merge, there aren't any other issues as far as I can tell.