Make team_id optional for admin_users_list

[hello-ashleyintech]

Summary

This PR fixes issue #1724 and changes the team_id param to optional in the Python SDK. It is marked as optional in the public facing API docs: https://api.slack.com/methods/admin.users.list

Category

• slack_sdk.web.WebClient (sync/async) (Web API client)
• slack_sdk.webhook.WebhookClient (sync/async) (Incoming Webhook, response_url sender)
• slack_sdk.socket_mode (Socket Mode client)
• slack_sdk.signature (Request Signature Verifier)
• slack_sdk.oauth (OAuth Flow Utilities)
• slack_sdk.models (UI component builders)
• slack_sdk.scim (SCIM API client)
• slack_sdk.audit_logs (Audit Logs API client)
• slack_sdk.rtm_v2 (RTM client)
• /docs (Documents)
• /tutorial (PythOnBoardingBot tutorial)
• tests/integration_tests (Automated tests for this library)

Requirements

• I've read and understood the Contributing Guidelines and have done my best effort to follow them.
• I've read and agree to the Code of Conduct.
• I've run python3 -m venv .venv && source .venv/bin/activate && ./scripts/run_validation.sh after making the changes.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 84.88%. Comparing base (b401e58) to head (c28d284).
⚠️ Report is 1 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@ Coverage Diff @@## main #1725 +/- ##
==========================================
- Coverage 84.91% 84.88% -0.04% 
==========================================
Files 113 113 Lines 12895 12895 ==========================================
- Hits 10950 10946 -4 - Misses 1945 1949 +4 

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[WilliamBergamin]

This looks good to me 🚀 thanks for putting this together