fix: add packaging to requirements.txt

[wangzelin007]

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Add explicit packaging dependency to fix extension release pipeline failure.
The extension release pipeline is failing with the following error:

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

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? (pip install wheel==0.30.0 required)
• My extension version conforms to the Extension version schema

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]

️✔️Azure CLI Extensions Breaking Change Test

️✔️Non Breaking Changes

[azure-client-tools-bot-prd]

Hi @wangzelin007,
Please write the description of changes which can be perceived by customers into HISTORY.rst.
If you want to release a new extension version, please update the version in setup.py as well.

[yonzhan]

Thank you for your contribution! We will review the pull request and get back to you soon.

[github-actions]

The git hooks are available for azure-cli and azure-cli-extensions repos. They could help you run required checks before creating the PR.

Please sync the latest code with latest dev branch (for azure-cli) or main branch (for azure-cli-extensions).
After that please run the following commands to enable git hooks:

pip install azdev --upgrade
azdev setup -c <your azure-cli repo path> -r <your azure-cli-extensions repo path>

[github-actions]

• For more info about extension versioning, please refer to Extension version schema

[Copilot]

Pull request overview

This PR addresses an Azure DevOps extension release pipeline failure by adding an explicit missing Python dependency (packaging) required by CI helper scripts under scripts/ci.

Changes:

• Add packaging to the scripts/ci/avail-ext-doc/requirements.txt dependency list to ensure the pipeline environment includes it.