fix(core): add a polling interval in Dispenser

[ManueleSigona]

Proposed Changes

Add an interval in the polling loop of Dispenser, so that agents don't spin up the CPU unnecessarily.

Linked Issues

442

Types of changes

What type of change does this pull request make (put an x in the boxes that apply)?

• [x] Bug fix (non-breaking change that fixes an issue).
• [ ] New feature added (non-breaking change that adds functionality).
• [ ] Breaking change (fix or feature that would cause existing functionality to stop working as expected).
• [ ] Documentation update.
• [ ] Something else (e.g., tests, scripts, example, deployment, infrastructure).

Checklist

Put an x in the boxes that apply:

• [x] I have read the CONTRIBUTING guide
• [x] Checks and tests pass locally

If applicable

• [ ] I have added tests that prove my fix is effective or that my feature works
• [ ] I have checked that code coverage does not decrease
• [ ] I have added/updated the documentation

Further comments

[if this is a relatively large or complex change, kick off a discussion by explaining why you chose the solution you did, what alternatives you considered, etc...]