* Trigger workflow on any push or pull request.
* Conditionally run Codecov Upload and Deploy *only* on `spulec/moto` repository.
This allows contributors to get CI results on their forked repo before
submitting PRs to `moto`. Previously, forked repos could run the actions
but would fail (rightfully) on the steps that should only be run on the
main repo (and require tokens/secrets).
