feat: add team.externalTeams.list

[WilliamBergamin]

Summary

This PR implements the team.externalTeams.list method for the python clients

Category (place an x in each of the [ ])

• 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-src (Documents, have you run ./scripts/docs.sh?)
• /docs-src-v2 (Documents, have you run ./scripts/docs-v2.sh?)
• /tutorial (PythOnBoardingBot tutorial)
• tests/integration_tests (Automated tests for this library)

Requirements (place an x in each [ ])

• 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

Attention: Patch coverage is 45.45455% with 18 lines in your changes missing coverage. Please review.

Project coverage is 84.88%. Comparing base (75997b2) to head (c08f10d).

Files	Patch %	Lines
slack_sdk/web/async_client.py	45.45%	6 Missing ⚠️
slack_sdk/web/client.py	45.45%	6 Missing ⚠️
slack_sdk/web/legacy_client.py	45.45%	6 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1512      +/-   ##
==========================================
- Coverage   85.04%   84.88%   -0.16%     
==========================================
  Files         112      112              
  Lines       12440    12473      +33     
==========================================
+ Hits        10579    10588       +9     
- Misses       1861     1885      +24     

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[filmaj]

LGTM but let's hold off on merging until the API goes public.

[seratch]

Thanks for working on it! It seems the endpoint is not yet public. Let's hold off merging this PR until the API becomes publicly available.

[seratch]

The list of methods is the output by this JS script. "team.externalTeams.list" is not yet public, so let's hold off making the manual change here until it becomes public.

[WilliamBergamin]

Sounds good 👍

[filmaj]

@WilliamBergamin this API is now live, so when ready, we should merge and release.

[seratch]

If you have the bandwidth, adding an integration tests for this API call is a great addition for safety and future maintenance (but it's optional)