Add python urllib3 support

Hello.

As we can read on AWS Blog requests is not supported by default in AWS Lambda function. It would be helpful to have urllib3 in Code snippet - "Python - urllib3"

The upcoming changes to AWS SDK

One of the main changes is that the requests library was replaced with urllib3. Additionally, the requests dependency was also unvendored, meaning Botocore can now support a range of versions of urllib3, instead of relying on a specific version. From version 1.13.0, the requests module is no longer part of the AWS SDK for Python. These changes create additional flexibility for Python developers, and can result in performance improvements for applications using Botocore.

Although the SDK has removed the requests module, the Lambda service continues to bundle the requests module in the AWS SDK until January 30, 2021. This is so builders have additional time to decide on the best course of action for their Python Lambda functions that rely on the requests module.

Thanks,
Wojtek

Locate the Python code-snippet generator and the existing Python requests example, then inspect how snippets are represented and tested. Add the requested Python urllib3 snippet for AWS Lambda use and verify that the generator produces the expected code snippet.