Security patches for external dependencies and a fix for exam creation with optional Chrome Extension.

• Fix POST /exams returning 422 when setting chrome_extension_required=false: Creating an exam via POST /api/v3/exams with chrome_extension_required set to false (or 0) now succeeds (201) when the institute has allow_chrome_extension_optional=true, instead of returning 422.

• Various security patches of external dependencies.