### Is there an existing issue for this?

- [X] I have searched the existing issues

### Current Behavior

APiGateway Model that being created by CDK project stores the JSON schema with a single quotes instead of double quotes which leading to an error in parsing this json object. 

you can refere to this article to see the steps 

https://dev.to/dvddpl/reduce-lambda-invocations-and-code-boilerplate-by-adding-a-json-schema-validator-to-your-api-gateway-15af

and it works fine on AWS account 

also you can look on the attached image how localstack stores the JSON object with a single quotes, I tried to edit it manually through UI but it return it back with single quotes

![Screen Shot 2022-10-18 at 4 28 08 PM](https://user-images.githubusercontent.com/106184681/196769273-0834865a-2fb3-4efc-b3a9-9da6b2ad511d.png)

### Expected Behavior

store the json schema in correct JSON format

### How are you starting LocalStack?

With the `localstack` script

### Steps To Reproduce

#### How are you starting localstack (e.g., `bin/localstack` command, arguments, or `docker-compose.yml`)

    localstack start

#### Client commands (e.g., AWS SDK code snippet, or sequence of "awslocal" commands)

    cdklocal deploy


### Environment

```markdown
- OS:OSX
- LocalStack: 1.0.4
```


### Anything else?

_No response_
deploy_cfn_template, snapshot, aws_client, s3_bucket
):
    
    swagger_template = load_file(os.path.join(os.path.dirname(__file__), "../../files/pets.json"))
    key_name = "swagger-template-pets.json"
    response = aws_client.s3.put_object(Bucket=s3_bucket, Key=key_name, Body=swagger_template)
    object_etag = response["ETag"]
    stack = deploy_cfn_template(
        template_path=os.path.join(
            os.path.dirname(__file__), "../../templates/apigateway_integration_from_s3.yml"
        ),
        parameters={
            "S3BodyBucket": s3_bucket,
            "S3BodyKey": key_name,
            "S3BodyETag": object_etag,
        },
        max_wait=120,
    )
    snapshot.add_transformer(snapshot.transform.cloudformation_api())
    snapshot.add_transformer(snapshot.transform.apigateway_api())
    snapshot.add_transformer(snapshot.transform.regex(stack.stack_name, "stack-name"))
    rest_api_id = stack.outputs["RestApiId"]
    rest_api = aws_client.apigateway.get_rest_api(restApiId=rest_api_id)
    snapshot.match("rest-api", rest_api)
    resources = aws_client.apigateway.get_resources(restApiId=rest_api_id)
    resources["items"] = sorted(resources["items"], key=itemgetter("path"))
    snapshot.match("resources", resources)
def test_cfn_apigateway_rest_api(deploy_cfn_template, aws_client):