SyntaxWarning for python string \| with sufficiently new python version

[bernstei]

Running generate_guidance.py under python 3.12 leads to many SyntaxWarning, e.g.

./scripts/generate_guidance.py:2112: SyntaxWarning: invalid escape sequence '\|'
  rule_id=rule_yaml['id'].replace('|', '\|'),

It appears that most recent python syntax interprets '\|' as an attempt to escape the |. I think it can be replaced with r'\|' or '\\|', but a, I'm not 100% sure this is right, and b, I'm not sure what python versions this project intends to support and whether they support this new raw string syntax.