I want to change the Stage created when creating API Gateway with AWS SAM from Prod to a custom name

Hello.

I am creating an API Gateway using AWS SAM.
At that time, I am trying to name "dev" as "StageName".
However, when I actually deploy it, a stage named "Prod" is created.
Is it not possible to set a custom name for an API Gateway stage in AWS SAM?
I checked the GitHub issue below, but the issue was not resolved.
https://github.com/aws/serverless-application-model/issues/191

AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31

Globals:
  Api:
    OpenApiVersion: 3.0.2

Parameters:
  Stage:
    Type: String
    Default: dev

Resources:
  ServerlessRestApi:
    Type: AWS::Serverless::Api
    Properties:
      OpenApiVersion: 3.0.2
      StageName: !Ref Stage
      Name: !Sub "${Stage}-Api"

  HelloWorldFunction:
    Type: AWS::Serverless::Function
    Properties:
      CodeUri: hello_world/
      Handler: app.lambda_handler
      Runtime: python3.9
      Architectures:
        - x86_64
      Events:
        HelloWorld:
          Type: Api
          Properties:
            Path: /hello
            Method: get
            RestApiId: !Ref ServerlessRestApi

Outputs:
  CsrfTokenApiUrl:
    Value: !Sub "https://${ServerlessRestApi}.execute-api.${AWS::Region}.amazonaws.com/${Stage}/hello"

samconfig.toml is as follows.

version=0.1

[development.deploy.parameters]
stack_name = "dev-api-stack"
resolve_s3 = true
s3_prefix = "dev-api-stack"
region = "ap-northeast-1"
confirm_changeset = true
capabilities = "CAPABILITY_IAM"
disable_rollback = true
parameter_overrides = [
    "Stage=dev"
]
image_repositories = []

app.py looks like this:

def lambda_handler(event, context):
    return {
        "statusCode": 200,
        "body":"message: hello world",
    }