calling as_dict() on default instantiated Attempt now doesn't raise TypeError

[leondz]

before this PR:

>>> from garak.attempt import Attempt
>>> a = Attempt()
>>> a.as_dict()
Traceback (most recent call last):
  File "<python-input-8>", line 1, in <module>
    a.as_dict()
    ~~~~~~~~~^^
  File "/home/lderczynski/dev/garacc/garak/attempt.py", line 268, in as_dict
    "prompt": asdict(self.prompt),
              ~~~~~~^^^^^^^^^^^^^
  File "/home/lderczynski/anaconda3/envs/garak/lib/python3.13/dataclasses.py", line 1358, in asdict
    raise TypeError("asdict() should be called on dataclass instances")
TypeError: asdict() should be called on dataclass instances

PR has Attempt.as_dict() only call dataclass.asdict() on Attempt.prompt if Attempt.prompt is not None

after:

>>> from garak.attempt import Attempt
>>> a = Attempt()
>>> a.as_dict()
{'entry_type': 'attempt', 'uuid': '51c21869-ab75-4b7a-9f59-8511a6039189', 'seq': -1, 'status': 0, 'probe_classname': None, 'probe_params': {}, 'targets': [], 'prompt': None, 'outputs': [], 'detector_results': {}, 'notes': {}, 'goal': None, 'conversations': [{'turns': [], 'notes': {}}], 'reverse_translation_outputs': []}

PR also adds test that instantiates an Attempt and calls its as_dict()

[jmartin-tech]

Makes sense to me.

[erickgalinkin]

cough I like it.