[docs] Updated links to django docs

[skip ci]

Author: nemesifier

docs/developer/admin-theme.rst

@@ -122,7 +122,7 @@ customize admin theme.
     to use the ``STATICFILES_DIR`` setting in ``settings.py``.
 
     You can learn more in the `Django documentation
-    <https://docs.djangoproject.com/en/3.0/ref/settings/#std:setting-STATICFILES_DIRS>`_.
+    <https://docs.djangoproject.com/en/4.2/ref/settings/#std:setting-STATICFILES_DIRS>`_.
 
 Extend Admin Theme Programmatically
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

docs/developer/admin-utilities.rst

@@ -146,7 +146,7 @@ by modifying ``InputFilter`` as following:
 
 To know about other lookups that can be used please check `Django Lookup
 API Reference
-<https://docs.djangoproject.com/en/3.2/ref/models/lookups/#django.db.models.Lookup>`__
+<https://docs.djangoproject.com/en/4.2/ref/models/lookups/#django.db.models.Lookup>`__
 
 ``openwisp_utils.admin_theme.filters.SimpleInputFilter``
 --------------------------------------------------------