bpo-45457: Minor fix to documentation for SSLContext.load_default_certs. (GH-28947) (GH-29373)

Specify that SSLContext.set_default_verify_paths is called on ALL systems.

The code of SSLContext.load_default_certs was changed in bpo-22449 to do this,
this fix corrects the documentation to match that change.
(cherry picked from commit 3551bf16ee5c25b6349209dd30e032f0f3b9ace3)

Co-authored-by: LincolnPuzey <lincoln@puzey.dev>