make default regex raw to remove python 3.12 warnings

[jmartin-tech]

Fix #802

Update regex default string to remove python 3.12 warning:

Using Python 3.12+

Before:

🦜 loading generator: Test: Lorem Ipsum
📜 reporting to /Users/jemartin/.local/share/garak/garak_runs/garak.3d0391eb-c705-4964-a1b9-01e413d23d86.report.jsonl
🕵️  queue of probes: atkgen.Tox
/Users/jemartin/Projects/nvidia/garak/garak/probes/atkgen.py:63: SyntaxWarning: invalid escape sequence '\<'
  "red_team_postproc_rm_regex": "\<\|.*",
🔴🪖  🦜 loading generator: Hugging Face 🤗 pipeline: leondz/artgpt2tox
atkgen.Tox                                                                toxicity.ToxicCommentModel: PASS  ok on    5/   5
📜 report closed :) /Users/jemartin/.local/share/garak/garak_runs/garak.3d0391eb-c705-4964-a1b9-01e413d23d86.report.jsonl
📜 report html summary being written to /Users/jemartin/.local/share/garak/garak_runs/garak.3d0391eb-c705-4964-a1b9-01e413d23d86.report.html
✔️  garak run complete in 15.74s

After:

garak LLM vulnerability scanner v0.9.0.14.post1 ( https://github.com/leondz/garak ) at 2024-07-30T15:55:00.122626
🦜 loading generator: Test: Lorem Ipsum
📜 reporting to /Users/jemartin/.local/share/garak/garak_runs/garak.87a12a50-d726-46fe-b0eb-c0e28f30cc9e.report.jsonl
🕵️  queue of probes: atkgen.Tox
🔴🪖  🦜 loading generator: Hugging Face 🤗 pipeline: leondz/artgpt2tox
atkgen.Tox                                                                toxicity.ToxicCommentModel: PASS  ok on    5/   5
📜 report closed :) /Users/jemartin/.local/share/garak/garak_runs/garak.87a12a50-d726-46fe-b0eb-c0e28f30cc9e.report.jsonl
📜 report html summary being written to /Users/jemartin/.local/share/garak/garak_runs/garak.87a12a50-d726-46fe-b0eb-c0e28f30cc9e.report.html
✔️  garak run complete in 33.71s