Allow version number configuration

[BronsonQuick]

We should add the ability to optionally specify a version number instead of @latest.

I was setting up a development machine which uses https://github.com/Chassis/core_dev and during provisioning there was an error with the npm install command because WordPress core requires "npm": ">=6.14.8 <7". Adding the ability to specify a version in a config file will help us to fix this issue.

Currently the @latest command installs version 9.4.0.