Fickling has Code Injection vulnerability via pty.spawn()

Fickling is a Python pickling decompiler and static analyzer. Versions prior to 0.1.6 had a bypass caused by `pty` missing from the block list of unsafe module imports. This led to unsafe pickles based on `pty.spawn()` being incorrectly flagged as `LIKELY_SAFE`, and was fixed in version 0.1.6. This impacted any user or system that used Fickling to vet pickle files for security issues.