Integrate cisco-ai-defense/pickle-fuzzer

[thomas-chauchefoin-tob]

Fickling is among the projects Cisco tested, without being directly named: https://blogs.cisco.com/ai/hardening-pickle-file-scanners. We should integrate their test cases to fickling.

We can also integrate cisco-ai-defense/pickle-fuzzer in the CI with google/atheris. It has to be optional as we didn't implement support for all opcodes and we'll have to fix these before we get anything meaningful out of the tool.