Allow Mangum to remove certain aws reponse headers from api gateway response

[amieka]

Problem: Currently Mangum injects the following headers in the api gateway response for an aws lambda integration

x-amz-apigw-id
x-amzn-requestid 
x-amzn-trace-id

This exposes additional information that the client doesn't need to know.

Proposal:

Allow Mangum to take optional parameter say exclude_header_keys=[] at the application mounting step.

An Example of that would look like.

from fastapi import FastAPI

app = FastAPI()

handler = Mangum(app, exclude_header_keys=[]

[jordaneremieff]

Hi @amieka,

I've given this some thought and decided it should okay to include this new parameter - let's go with a new parameter named exclude_headers.

Would you be able to create a PR?

[amieka]

Hi @jordaneremieff I can take a stab it. Thank you