GitHub Action btwn QCEl and QCSk

[loriab]

Description

Continues from #204. Generate schema from pydantic qcel for models owned by qcsk, compare them, and issue PR to latter in case change to qcel would affect qcsk. Part of MolSSI/QCSchema#68 effort to consolidate single source of truth here and community discussion there.

• because secrets not passed to PRs from forks, these'll have to be internal PRs. I don't understand how codecov is working from fork PRs.
• I think this is pretty much ready. the whole sequence is:
  • fix schema for Array classes #217 needs to happen here
  • QCSk repo needs to switch to JSON files for each model instead of single python module
  • then the target in the action can switch from loriab/QCSchema to upstream
  • I'm thinking of leaving this PR as-is at the push branch stage, then adding https://github.com/marketplace/actions/github-pull-request-action to QCSk to listen for qcel-* branches

Changelog description

Status

• Code base linted
• Ready to go

[codecov]

Codecov Report

Merging #218 into master will decrease coverage by 0.01%.
The diff coverage is n/a.

[loriab]

This has been subsumed into #237