Support dramatiq 2.x

A new major version of dramatiq came out recently. Our tests are failing on it. Fix the tests and see whether the integration itself needs adapting.

Changelog: https://dramatiq.io/changelog.html
Failing tests: https://github.com/getsentry/sentry-python/actions/runs/19530147877/job/55910978464?pr=5122