chore: Fix update_deps workflow

[lym953]

What does this PR do?

The update_deps workflow is broken. This PR fixes it.

Motivation

Testing Guidelines

Steps:

1. In repo settings, allow the env protected-main-env to be run on the branch yiming.luo/fix-upgrade
2. Manually trigger this workflow
   Result:
3. The workflow run was successful: https://github.com/DataDog/datadog-lambda-python/actions/runs/15450123842
4. A PR is generated: Update Dependencies #606

Additional Notes

Types of Changes

• Bug fix
• New feature
• Breaking change
• Misc (docs, refactoring, dependency upgrade, etc.)

Check all that apply

• This PR's description is comprehensive
• This PR contains breaking changes that are documented in the description
• This PR introduces new APIs or parameters that are documented and unlikely to change in the foreseeable future
• This PR impacts documentation, and it has been updated (or a ticket has been logged)
• This PR's changes are covered by the automated tests
• This PR collects user input/sensitive content into Datadog
• This PR passes the integration tests (ask a Datadog member to run the tests)

[lym953]

Thanks @purple4reina for suggesting this fix