Keep the Approach base class up to date

[gukoff]

Purpose

Approach base class was not up to date with the newer run() schemas.

Using abc, we get more confidence that all subclasses conform with the declared schema.

Does this introduce a breaking change?

[ ] Yes
[x] No

Pull Request Type

What kind of change does this Pull Request introduce?

[ ] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[x] Refactoring (no functional changes, no api changes)
[ ] Documentation content changes
[ ] Other... Please describe:

[gukoff]

@tonybaloney done!

[pamelafox]

@gukoff Thanks for this PR, I ended up making the same changes in a recent PR that changed the interface, so we don't need to merge this anymore.