Update `bullmq` dependency to v2.0.0

[tolgap]

Is there an existing issue that is already proposing this?

• [X] I have searched the existing issues

Is your feature request related to a problem? Please describe it

BullMQ recently released version 2. It contains breaking changes. Namely the removal of QueueScheduler class. The QueueScheduler class isn't needed anymore to support delayed jobs.

Describe the solution you'd like

• Upgrade the peerDependency to "bullmq": "^2.0.0"
• Remove usage of QueueScheduler.

Teachability, documentation, adoption, migration strategy

https://github.com/taskforcesh/bullmq/releases/tag/v2.0.0

What is the motivation / use case for changing the behavior?

Have an upgrade path for my project that uses @nestjs/bullmq.

[kamilmysliwiec]

Would you like to create a PR for this issue @tolgap? 🙌

[michael-land]

Hi, @kamilmysliwiec someone already made a PR.