fix: SslCheck rejected requests with a matching verification token

[sahiljagtap08]

Summary

When an App or AsyncApp is built with verification_token, the SslCheck middleware got the check backwards:

• an ssl_check request whose token matched returned 401
• a request whose token did not match returned 200
• a request with no token field raised KeyError, which became a 500

The helper returned True on a match, while the caller treated True as the error case. The existing tests never set verification_token, so this was not covered.

Changes in slack_bolt/middleware/ssl_check/:

• The error response is returned only when a token is configured and the request's token is missing or wrong.
• The token is read with body.get() so a missing token is rejected instead of crashing.
• The async middleware inherits the helper, so it gets the same fix with a matching one-line change.

Testing

Added test_ssl_check_with_verification_token to both tests/scenario_tests/test_ssl_check.py and tests/scenario_tests_async/test_ssl_check.py. Each covers a matching token (200), a wrong token (401), and a missing token (401). The sync test fails on main and passes with this change. Ran ./scripts/format.sh, ./scripts/lint.sh, ./scripts/run_mypy.sh, and the ssl_check test files.

Category

• slack_bolt.App and/or its core components
• slack_bolt.async_app.AsyncApp and/or its core components
• Adapters in slack_bolt.adapter
• Others

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

Fixes #1595