Update Lambdas to non-deprecated Python runtime & update CDK to v2

[ceholden]

Description

This project deploys a number of Lambda functions that are running using the Python 3.8 runtime. This runtime was deprecated on October 14th, 2024, which ends technical support and potentially stops updates to the runtime, including security updates. After Mar 31, 2025 we will not be able to update the functions, preventing us from deploying bug fixes or new features.
https://docs.aws.amazon.com/lambda/latest/dg/lambda-runtimes.html#runtimes-deprecated

As of June 1, 2023 the AWS Cloud Development Toolkit (CDK) reached end of life, removing technical support and updates, including security updates.
https://aws.amazon.com/blogs/devops/cdk-v1-end-of-support/

To get out ahead of any issues these deprecations could cause, we should upgrade our Lambda functions to run on a newer version of the Python runtime (e.g., supported versions like Python 3.11 or 3.12) and be deployed using AWS CDK v2.

Acceptance Criteria

• Lambda functions run on a recent, supported version of the Python runtime
• Lambda functions and other resources are deployed using AWS CDK v2

[ceholden]

This is complete as of https://github.com/NASA-IMPACT/hls-sentinel2-downloader-serverless/releases/tag/v1.0.12 release