fix type hint for event constraint to allow None subtypes

[alexrashed]

This PR adjusts the type hints for event constraints such that the type hint explicitly allows None for the constraint.
The additional optional represents the check implemented here:

bolt-python/slack_bolt/listener_matcher/builtins.py

Lines 146 to 148 in 54114ca

	if expected_subtype is None:
	# "subtype" in constraints is intentionally None for this pattern
	return "subtype" not in event_payload

This change allows a type-safe usage of the explicit None subtype constraint:

@app.event(
    event={
        "type": "message",
        "subtype": None
    }
)
def handle_messages_without_subtype(client: WebClient, event: dict) -> None:
    ...

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

• slack_bolt.App and/or its core components
• slack_bolt.async_app.AsyncApp and/or its core components
• Adapters in slack_bolt.adapter
• Document pages under /docs
• Others: builtin matchers

Requirements (place an x in each [ ])

Please read the Contributing guidelines and Code of Conduct before creating this issue or pull request. By submitting, you are agreeing to those rules.

• 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 ./scripts/install_all_and_run_tests.sh after making the changes.

PS.: Thanks for the awesome framework, it really is fun to use! 💯
PPS.: The CLA tooling described in the contribution guideline doesn't really work for me (couldn't select anything), but I explicitly accepted the conditions by signing off the commit.

[seratch]

Hi @alexrashed, thanks for making this improvement! The changes on the docs and code are fine but can you revert the changes under docs/api-docs/? We will generate the api-docs when making a new release.

[seratch]

@alexrashed

PS.: Thanks for the awesome framework, it really is fun to use! 💯

Thank you! I am so glad to hear this 😃

PPS.: The CLA tooling described in the contribution guideline doesn't really work for me (couldn't select anything), but I explicitly accepted the conditions by signing off the commit.

The CLA Assistant service might have some issues when you accessed. Can you try visiting https://cla-assistant.io/slackapi/bolt-python again and signing our CLA there with the email address that you used for the commit in this PR?

[CLAassistant]

All committers have signed the CLA.

[alexrashed]

Thanks for the fast response! After some retries signing the CLA worked and I reverted the changes to the auto-generated docs.

[seratch]

Looks great to me. After merging this PR., I will apply the corresponding change to Japanese document page.

[codecov]

Codecov Report

Merging #616 (ea02b45) into main (54114ca) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main     #616   +/-   ##
=======================================
  Coverage   91.46%   91.46%           
=======================================
  Files         170      170           
  Lines        5766     5766           
=======================================
  Hits         5274     5274           
  Misses        492      492           

Impacted Files	Coverage Δ
slack_bolt/app/app.py	87.69% <ø> (ø)
slack_bolt/app/async_app.py	94.19% <ø> (ø)
slack_bolt/listener_matcher/builtins.py	93.83% <100.00%> (ø)

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[seratch]

@alexrashed Thanks for your contribution 🎉