Generated response dicts don't include `'ResponseMetadata'`

[fish-face]

e.g.

import boto3
session = boto3.Session()
s3 = session.resource('s3', ...)
bucket = s3.Bucket('foo')
object = bucket.Object('bar')
response = object.get()
print(f'Got status {response["ResponseMetadata"]["HTTPStatusCode"]}')

mypy on the above results in:

file.py:8: error: TypedDict "GetObjectOutputTypeDef" has no key 'ResponseMetadata'

However the actual returned response dict does have this key.