add workflow that reports back to a PR whether schema has changed

[satra]

It would be good to just add a PR bot that checks schema change and reports back to a PR. we often check on this by turning release label on and then turning it off.

[yarikoptic]

try removing this line
https://github.com/dandi/dandischema/blob/HEAD/.github/workflows/test-schema.yml#L11
if that is what you are looking for ?

[satra]

it would be a combination of that if and the exitcode later in the workflow. we don't want the test to fail, but just inform that a new schema release may be necessary with the PR.

[satra]

perhaps using something like this: https://github.com/marketplace/actions/add-pr-comment