Allow kwargs in lambda handlers

[SamuelM333]

What does this PR do?

Allows kwargs in lambda handlers.

Motivation

Our serverless project has kwargs in the lambda handlers to make testing easier. If we add the datadog lambda wrapper, the tests break.

Example of kwargs in a lambda handler:

SQS = boto3.client('sqs', region_name='us-east-1')
DYNAMO_CLIENT = boto3.resource('dynamodb', region_name='us-east-1')
LOGGER = setup_logger()

def lambda_handler(event, context, logger=LOGGER, sqs_client=SQS, dynamodb_client=DYNAMO_CLIENT):
    pass

Testing Guidelines

I ran ./scripts/run_tests.sh and all tests were OK. I also installed locally this version of the package on my project and my tests now pass.

Additional Notes

I also modified the run_tests.sh shebang to #!/bin/bash since the PYTHON_VERSIONS array was declared with bash-specific syntax and trying to run ./scripts/run_tests.sh with sh failed.

[tianchu]

@SamuelM333 Thanks for submitting the PR! I left a small comment and everything else looks great to me 👍

[tianchu]

Is it necessary to pass kwargs to _before() and _after()? I don't think any of the datadog logic depends (or should depend) on the kwargs.

[SamuelM333]

Makes sense. Gonna remove that.

[tianchu]

@SamuelM333 The PR is now merged and will be included in the next release. Thanks for your contribution 👍