KeyError when optional CLI arg --parent-activity is omitted

[andmat900]

Description

When the optional --parent-activity argument is not given to etosctl, there is a KeyError before None can be assigned.

Traceback (most recent call last):
  File "/home/user/etos/cli/etosctl/__main__.py", line 106, in run
    main(sys.argv[1:])
  File "/home/user/etos/cli/etosctl/__main__.py", line 101, in main
    main.start()
  File "/home/user/etos/cli/etosctl/__main__.py", line 93, in start
    self.run(args)
  File "/home/user/etos/cli/etosctl/command/command.py", line 107, in run
    return self.subcommand.run(args)
  File "/home/user/etos/cli/etosctl/command/command.py", line 107, in run
    return self.subcommand.run(args)
  File "/home/user/etos/cli/etosctl/command/command.py", line 107, in run
    return self.subcommand.run(args)
  File "/home/user/etos/cli/etos_client/etos/v1alpha/subcommands/start.py", line 73, in run
    result = etos.run()
  File "/home/user/etos/cli/etos_client/etos/v1alpha/etos.py", line 80, in run
    response, error = self.__start()
  File "/home/user/etos/cli/etos_client/etos/v1alpha/etos.py", line 101, in __start
    request = self.start_request.from_args(self.args)
  File "/home/user/etos/cli/etos_client/etos/v0/schema/request.py", line 42, in from_args
    parent_activity=args["--parent-activity"] or None,
KeyError: '--parent-activity'/

Additional Context

No response

Logs

Expected Behavior

It shall be possible to use etosctl without providing --parent-activity.

Steps To Reproduce

No response

The version of this project/repo, if applicable

No response

The version/edition of the Eiffel Protocol used, if applicable

No response