Update flask-signup-datasources.rb
Update flask-signup-datasources.rb

Update AMI references
gavinaws/py-flask-signup-datasources,amyzhang0330/py-flask-signup,gavinaws/py-flask-signup-datasources,gavinaws/py-flask-signup-datasources,amyzhang0330/py-flask-signup,amyzhang0330/py-flask-signup