* gnu/packages/django.scm (python-django-auth-ldap): Update to 4.0.0.
[arguments]: Rewrite with gexp and remove inputs labels. Do a "manual"
PEP517-style build.
[native-inputs]: Remove PYTHON-MOCK. Change from OPENLDAP to OPENLDAP-2.6.
Add PYTHON-PYPA-BUILD, PYTHON-PIP, PYTHON-SETUPTOOLS-SCM, PYTHON-TOML, and
PYTHON-WHEEL.