py-v1.13.8 - cascade names the delete handlers Django 6.1's DB_CASCADE skips (#179)

Added

• cascade names the delete handlers Django 6.1's DB_CASCADE skips (#179).
  With on_delete=models.DB_CASCADE the database deletes the child
  rows itself, so Django never sends pre_delete / post_delete for them: a
  post_delete handler that removes the uploaded file, writes the audit log
  or busts a cache just stops running, with no error. cascade (CLI and the
  MCP cascade_preview tool) now lists each @receiver for that model, or
  for every model, under the affected relation as skipped_receivers, and
  the text output prints them with file and line. The signal graph is only
  built when a DB_CASCADE relation exists.

• Tested on Python 3.15 (#180). CI gained a Python 3.15 + Django 6.1 leg,
  and the package metadata lists 3.15.