input: Write a python function to read server configuration from a file.
  assert read_server_config('./configuracion/agente-servidor.cfg') == {'puerto': 6470, 'clave': 'root', 'clientes': 'some_clients'}
  assert read_server_config('./configuracion/missing.cfg') == {'puerto': 6470, 'clave': 'root', 'clientes': None}
output: def read_server_config(filepath):
      default_config = {'puerto': 6470, 'clave': 'root', 'clientes': None}
      try:
          with open(filepath, 'r') as file:
              lines = file.readlines()
              for line in lines:
                  key, value = line.strip().split('=')
                  if key in default_config:
                      default_config[key] = int(value) if key == 'puerto' else value
      except FileNotFoundError:
          pass
      return default_config