There is a new pull request by zdtcd against master on the void-packages repository

https://github.com/zdtcd/void-packages firefox
https://github.com/void-linux/void-packages/pull/16020

Firefox Updated to 70.0.1
Convenient update for nss 3.47 #15946 
Built on:
- [ ] x86_64
- [ ] x86_64-musl
- [ ] i686
- [ ] armv7hf
- [ ] armv7hf-musl
- [ ] aarch64
- [ ] aarch64-musl

Tested with:
- [ ] x86_64
- [ ] x86_64-musl

A patch file from https://github.com/void-linux/void-packages/pull/16020.patch is attached