{AKS} Fix live test execution by fixing version of vcrpy

[FumingZhang]

---

This checklist is used to make sure that common guidelines for a pull request are followed.

Fix the version of a lib vcrpy (used by testsdk) to 4.2.1 to fix live test execution. There're some compatibility issues between vcrpy>=4.3.0 and urllib3 (v1).

Related command

General Guidelines

• Have you run azdev style <YOUR_EXT> locally? (pip install azdev required)
• Have you run python scripts/ci/test_index.py -q locally?

For new extensions:

• My extension description/summary conforms to the Extension Summary Guidelines.

About Extension Publish

There is a pipeline to automatically build, upload and publish extension wheels.
Once your pull request is merged into main branch, a new pull request will be created to update src/index.json automatically.
You only need to update the version information in file setup.py and historical information in file HISTORY.rst in your PR but do not modify src/index.json.

[azure-client-tools-bot-prd]

Hi @FumingZhang,
If you want to release the new extension version.
Please write the description of changes into HISTORY.rst and update setup.py.

[yonzhan]

AKS