Refactor IMAP Tasks: Filter Allowed Attachment Types & Improve Code Quality
- Filter attachments to process only office files, PDFs, plain text, CSV, and RTF,
explicitly skipping common image MIME types.
- Use an explicit elif for clarity in attachment processing logic.
- Remove dead code by not reassigning the result of fetch_attachments_and_enqueue.
- Reformat log messages, docstrings, and break long lines to comply with PEP 8.
- Add clarifying comments for excluded image MIME types.