CI: run pyright and pytest on dev pull requests

[shellygr]

The dev branch carries work that should be usable before it is approved for master. Its
ruleset requires the pyright and pytest checks and has no bypass actors, but both workflows
trigger only on pull requests targeting main/master. A PR into dev therefore reports
neither check, and a required check that never reports blocks the merge indefinitely.

This adds dev to the branch filters of both workflows.

The same change was already applied directly on dev so mirrored PRs could merge. Landing it on
master too keeps the two branches from diverging in .github/workflows/ — otherwise every
future branch cut from master carries the narrower filters until a dev merge fixes them up.

No new CI cost: integration-tests.yml, the suite that submits real jobs to the live prover,
is schedule + workflow_dispatch only and is untouched here.