Is it possible to specify a second file to build requirements from using AWS Serverless Build?

Let's say I have a template.yaml which has the following resource:

Resources:
  TesterFunction:
    Type: AWS::Serverless::Function 
    Properties:
      CodeUri: test/
      Handler: app.tester
      Runtime: python3.7
      Events:
        TestFunc:
          Type: Api 
          Properties:
            Path: /tester 
            Method: get 

When I run sam build it automatically looks for requirements.txt in CodeUri path. Is there a way to specify a second requirements file to build from e.g env-requirements.txt?