Detection: add insecure-deserialization rule for Python (pickle / yaml.load)

[bkd-dotcom]

Add a rule flagging unsafe deserialization in Python.

Where: signetry_core/pipeline/findings/deterministic.py (_scan_python).

Detect: pickle.loads(...) / pickle.load(...) on non-constant input; yaml.load(x) without Loader=SafeLoader; marshal.loads.

Must NOT flag: yaml.safe_load(...), or yaml.load(x, Loader=yaml.SafeLoader).

Acceptance criteria:

• Rule id py.insecure-deserialization, category deserialization, CWE-502, severity HIGH.
• Tests: one vulnerable case detected, one safe case (safe_load) not flagged.
• pytest + ruff green.

[AdvaitVarhade]

hello i would like to work on this issue and implement the python insecure deserialization detection rule with full test coverage

[AdvaitVarhade]

i have implemented the insecure deserialization rule and opened pull request #91 please check and tell if any changes are required