Need a way to update the spec OpenAPI source from this repo

[ml-evs]

As it stands, we have to manually sync the openapi schemas from this package with the same files in the spec (https://github.com/Materials-Consortia/OPTIMADE/tree/develop/schemas); this hasn't been done for 3 months.

The suggestion is to add another GH action to make a PR against the spec when the version here has changed (https://github.com/marketplace/actions/create-pull-request).

[shyamd]

I don't think that action can commit to a different repo. The better way is probably to have the main OPTIMADE repo have this repo as a sub-module and respond to changes in this repo using dependabot.