Fix cookie extraction during OAuth for REST based AWS API GW + Lambda app

[naveensan1]

Summary:

This pull request is related to #379.

I too deployed a Bolt-python app to AWS Lambda, integrated with REST (format v1.0) based API GW. In the process of the verification of oauth redirect, the app could not be installed properly. Taking a look at the CloudWatch logs I could see the multivalueheader in the request had the key "cookie" instead of "Cookie" as is expected by "to_bolt_request".

   if cookies is None or len(cookies) == 0:
        # In the case of format v1
        multiValueHeaders = event.get("multiValueHeaders", {})
        cookies = multiValueHeaders.get("Cookie", [])

After modifying the following line to account for lower case "cookie", everything worked fine:

     cookies = multiValueHeaders.get("cookie", [])

I think the comment about to_bolt_request not supporting REST API can now be removed because I tried and it works

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.

[CLAassistant]

All committers have signed the CLA.

[codecov]

Codecov Report

Merging #451 (ee2c378) into main (4ec4444) will increase coverage by 0.00%.
The diff coverage is 100.00%.

❗ Current head ee2c378 differs from pull request most recent head cefccf6. Consider uploading reports for the commit cefccf6 to get more accurate results

@@           Coverage Diff           @@
##             main     #451   +/-   ##
=======================================
  Coverage   91.34%   91.34%           
=======================================
  Files         167      167           
  Lines        5499     5501    +2     
=======================================
+ Hits         5023     5025    +2     
  Misses        476      476           

Impacted Files	Coverage Δ
slack_bolt/adapter/aws_lambda/handler.py	95.83% <100.00%> (+0.11%)	⬆️

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[seratch]

Thank you!

[seratch]

Good catch 👍

[seratch]

👍