Fix #370 by adding an alias of next arg (next_) in middleware arguments

[seratch]

This pull request fixes #370. The essential change in this pull request is to add next_ to kwargs_injection names. With this fix, developers can use next_ in addition to next in the middleware method arguments.

@app.middleware
def just_call_next(next_):
    next_()

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

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.

[seratch]

comments for reviewers

[seratch]

Checking these test patterns should be helpful for knowing the purpose of the changes.

[seratch]

This is not an essential part of this PR. It's just a minor refactoring

[seratch]

Adding this enables bolt-python to resolve the alias name as well.

[codecov]

Codecov Report

Merging #394 (4a4105d) into main (c61206d) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main     #394   +/-   ##
=======================================
  Coverage   91.60%   91.61%           
=======================================
  Files         167      167           
  Lines        5384     5388    +4     
=======================================
+ Hits         4932     4936    +4     
  Misses        452      452           

Impacted Files	Coverage Δ
slack_bolt/kwargs_injection/async_utils.py	85.71% <ø> (ø)
slack_bolt/kwargs_injection/utils.py	85.71% <ø> (ø)
slack_bolt/logger/messages.py	90.62% <ø> (ø)
slack_bolt/middleware/async_custom_middleware.py	96.15% <ø> (ø)
slack_bolt/middleware/async_middleware.py	90.90% <ø> (ø)
...e/authorization/async_multi_teams_authorization.py	91.17% <ø> (ø)
...e/authorization/async_single_team_authorization.py	93.54% <ø> (ø)
...dleware/authorization/single_team_authorization.py	93.33% <ø> (ø)
slack_bolt/middleware/custom_middleware.py	100.00% <ø> (ø)
...listener_matches/async_message_listener_matches.py	100.00% <ø> (ø)
... and 11 more

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[mwbrooks]

Looks good to me! ✅

Just out of curiosity, is next_ a convention in Python? Rather than say nextMiddleware.

[seratch]

Just out of curiosity, is next_ a convention in Python? Rather than say nextMiddleware.

I think next_middleware is also fine but it may be a bit long (in comparison with other middleware args). As we use for syntax (for element in seq:) in most cases, it's rare to directly call next with an iterator. Having a kind of workaround name like this should make sense.