Duplicate task due to Sweeper reading stale workflowModel

[arorashivam]

Describe the bug
Duplicate task due to Sweeper reading stale workflowModel

Further debugging details, for e.g.

1. Sweeper fetches the workflowModel before acquiring the lock.
2. Meanwhile another thread updates the workflow model and releases the lock.
3. Sweeper now acquires the lock and triggers the decide using stale workflowModel.

Details
Conductor version: 3.20.0
Persistence implementation: Postgres
Queue implementation: Dynoqueues
Lock: Redis
Workflow definition: N/A
Task definition: N/A
Event handler definition: N/A

To Reproduce
Steps to reproduce the behavior:

1. Go to '...'
2. Click on '....'
3. Scroll down to '....'
4. See error

Expected behavior
No duplicate task

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Additional context
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