parsers: fix typing in socket.py

[mkmkme]

Pull Request check-list

Make mypy slightly happier by fixing some typing in socket.py

• [ ] Do tests and lints pass with this change?
• [ ] Do the CI tests pass with this change (enable it first in your forked repo and wait for the github action build to finish)?
• [ ] Is the new or changed code fully tested?
• [ ] Is a documentation update included (if this change modifies existing APIs, or introduces new ones)?
• [ ] Is there an example added to the examples folder (if applicable)?

Description of change