security/py-social-auth-core4: Update to 4.8.7

• For now, stick with this release, because newer versions starting with 4.9.0+ are not compatible with NetBox 4.6.

• Clean up stale entries from distinfo while I'm here.

Changelogs since 4.8.5:

https://github.com/python-social-auth/social-core/releases/tag/4.8.7
https://github.com/python-social-auth/social-core/releases/tag/4.8.6

MFH: 2026Q3
(cherry picked from commit d08240374611d414a4fb79a10d4297f3ef81ecdb)