Require on DESCRIPTION file gh to be exactly 1.2.0

[carlosparadis]

https://github.com/r-lib/gh/issues/181

Ran into this issue again after updating to R 4.0+, which forced the 1.4.0 version to be installed. I could not remember why my API data kept downloading the same first page repeatedly for Kaiaulu issue tracker.

Until it is resolved or I figure out what other versions are safer, probably best to restrict the version I know it works just in case.