fix(parser): Make ApiGateway version, authorizer fields optional

[walmsles]

**Issue #531 **

Description of changes:

Change to APIGatewayProxyEventModel to make "version" Optional
Change to APIGatewayEventRequestContext to make "authorizer" Optional

Checklist

• Meet tenets criteria
• Update tests
• Update docs
• PR title follows conventional commit semantics

Breaking change checklist

RFC issue #:

• Migration process documented
• Implement warnings (if it can live side by side)

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[boring-cyborg]

Thanks a lot for your first contribution! Please check out our contributing guidelines and don't hesitate to ask whatever you need.

[heitorlessa]

Thank you so much @walmsles !

Question: What's the type of API Gateway integration that makes this necessary?

In other words, how did you hit this issue?

[walmsles]

@heitorlessa I created a simple API using LAMBDA_PROXY integration that was very basic - no authentication just default setup for a quick POC test playing around with powertools and parser to see how it works, behaves.

I have also come across this problem setting up sample events using:

sam local generate-event apigateway aws-proxy

I used serverless framework to push the API up to my AWS account.

[heitorlessa]

Thanks a lot again @walmsles - Merging this now.

I've just tried deploying an API GW and I don't see those fields in the request too, so either we used an incorrect event or this changed -- hard to know the latter as there isn't an official schema yet.

cc @risenberg-cyberark -- I'll create an issue to create infrastructure for integ test so we can prevent this from happening in the future.

[codecov-commenter]

Codecov Report

Merging #532 (17af7af) into develop (5b87bb1) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff            @@
##           develop     #532   +/-   ##
========================================
  Coverage    99.23%   99.23%           
========================================
  Files          113      113           
  Lines         4468     4468           
  Branches       243      243           
========================================
  Hits          4434     4434           
  Misses          22       22           
  Partials        12       12           

Impacted Files	Coverage Δ
...lambda_powertools/utilities/parser/models/apigw.py	97.40% <100.00%> (ø)

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[boring-cyborg]

Awesome work, congrats on your first merged pull request and thank you for helping improve everyone's experience!