Don't panic on invalid version status

[m-aciek]

Fixes #327.

Example warning (CI):

2026-02-26 00:54:36,409 WARNING: Saw invalid version status '', expected to be one of EOL, bugfix, end-of-life, feature, in development, pre-release, prerelease, security, security-fixes, stable. Context: {'branch': '', 'pep': 826, 'status': '', 'first_release': '2027-10-06', 'end_of_life': '2032-10', 'release_manager': 'Savannah Ostrowski'}