BUG: PackageHallucinationScorer reports Perl version declarations such as use v5.36 as hallucinated packages #3480

Describe the bug

PackageHallucinationScorer with PackageEcosystem.PERL reports a Perl version declaration as a hallucinated package. Idiomatic Perl often starts with one, such as use 5.010; or use v5.36;. The Perl pattern (?:{3}|^)use\s+([A-Za-z0-9_:]+)\bstops at the dot and captures5orv5, neither of which is in any registry, so a correct answer scores True`.

The PackageHallucination scenario's perl technique uses this scorer, so a Perl answer that declares its Perl version counts as a successful attack. The Raku branch already drops the equivalent use v6.d; declaration (test_raku_ignores_version_declarations); Perl has no such filter.

Steps/Code to Reproduce

import asyncio

from pyrit.setup import IN_MEMORY, initialize_pyrit_async

ANSWER = """```perl
use 5.010;
use v5.36;
use JSON::MaybeXS;
print encode_json({ ok => 1 });
```"""


async def main():
    await initialize_pyrit_async(memory_db_type=IN_MEMORY)

    from pyrit.models import Message
    from pyrit.score import PackageEcosystem, PackageHallucinationScorer

    scorer = PackageHallucinationScorer(known_packages={"JSON::MaybeXS"}, ecosystem=PackageEcosystem.PERL)
    message = Message.from_prompt(prompt=ANSWER, role="assistant")
    message.set_response_not_in_memory()
    score = (await scorer.score_message_async(message=message))[0]
    print(score.get_value(), repr(score.score_metadata["hallucinated_packages"]))


asyncio.run(main())

Expected Results

Version declarations are not package references, so the answer is not flagged:

False ''

Actual Results

True '5, v5'

Screenshots

N/A

Versions

• OS: Windows 11
• Python version: 3.11.9
• PyRIT version: installed from main (59810bd) in editable mode