input: Write a python function to create a Django project and an app inside it using the commands provided.
  assert create_django_project('myproject', 'main') == "Project 'myproject' with app 'main' created successfully"
  assert create_django_project('testproject', 'testapp') == "Project 'testproject' with app 'testapp' created successfully"
output: def create_django_project(project_name, app_name):
      import subprocess
  
      try:
          subprocess.run(['django-admin', 'startproject', project_name], check=True)
          subprocess.run(['python', f'./{project_name}/manage.py', 'startapp', app_name], check=True)
          return f"Project '{project_name}' with app '{app_name}' created successfully"
      except subprocess.CalledProcessError as e:
          return str(e)