Closed issue by JamiKettunen on void-packages repository

https://github.com/void-linux/void-packages/issues/39226

Description:
As per https://endoflife.date/firefox 78 ESR has been EoL for nearly a year soon. According to a quick `grep -r` only the following consumers remain:
- [ ] [`0ad`](https://github.com/void-linux/void-packages/pull/46525)
- [x] [`cjs`](https://github.com/linuxmint/cjs/compare/5.6.1...1ef6934)
- [x] [`polkit`](https://github.com/void-linux/void-packages/pull/39203)

This would also contribute to #38229 ([`mozjs78`](https://github.com/void-linux/void-packages/blob/master/srcpkgs/mozjs78/template#L11) has `python-devel` in `makedepends`).

We should also keep in mind what happened with `mozjs60`: [5121c0f](https://github.com/void-linux/void-packages/commit/5121c0f) (`mozjs60: re-add as meta to allow people to upgrade their systems`) so the same thing doesn't happen again with the removal of `mozjs78`.