tests: Big push to get the tests to pass again. - Lots of fixes everywhere in the code. - Try to handle debug logging in the multiprocessing worker pool when running in pytest. Not perfect, but usable for now. - Replace all `.md` test files with `.html` since now a auto-format extension always sets the format. - Replace `out` with `outfiles` in most places since now blog archives are added to the bake output and I don't want to add expected outputs for blog archives everywhere.

# This is a utility module that can be used with any WSGI-compatible server
# like Werkzeug or Gunicorn. It returns a WSGI app for serving a PieCrust
# administration panel located in the current working directory.
import os
from piecrust.wsgiutil import get_admin_app


root_dir = os.getcwd()
app = get_admin_app(root_dir)
# Add this for `mod_wsgi`.
application = app