AWS::Serverless::Function does not support API Gateway Event pointing to auto publish Alias

## 1. Title
AWS::Serverless::Function does not support API Gateway Event pointing to auto publish Alias

## 2. Scope of request

Hello, my team is excited by the new Lambda Reserved Concurrency configuration that was recently launched. We currently use the AWS Serverless Transform and it does support the new field.
However, it doesn’t appear that Serverless transform allows us to point Lambda events such as API Gateway at a specific Alias of Lambda, therefore preventing us from utilizing the new reserved concurrency configuration.

## 3. Expected behavior
When defining an event for a serverless Lambda, I should be able to define that the auto-publish alias should be the target for the event.
## 6. Category (required) - Will help with tagging and be easier to find by other users to +1

Use the categories as displayed in the AWS Management Console (simplified):
Management (CloudTrail, Config...)

No repository files or tests are mentioned. Start by reviewing the AWS::Serverless::Function event behavior described here, including API Gateway targets, auto-publish aliases, and reserved concurrency; done means an API Gateway event can target the auto-publish alias.

Written by the indexing model from the issue text.