[docs] Updated refs 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/4.2/ref/settings/#std:setting-STATICFILES_DIRS>`_.
+    <https://docs.djangoproject.com/en/5.2/ref/settings/#std:setting-STATICFILES_DIRS>`_.
 
 Extend Admin Theme Programmatically
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

docs/developer/admin-utilities.rst

@@ -157,7 +157,7 @@ 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/4.2/ref/models/lookups/#django.db.models.Lookup>`__
+<https://docs.djangoproject.com/en/5.2/ref/models/lookups/#django.db.models.Lookup>`__
 
 ``openwisp_utils.admin_theme.filters.SimpleInputFilter``
 --------------------------------------------------------

docs/developer/custom-fields.rst

@@ -20,7 +20,7 @@ openwisp modules.
 ----------------------------------------------------
 
 This field extends Django's `BooleanField
-<https://docs.djangoproject.com/en/4.2/ref/models/fields/#booleanfield>`_
+<https://docs.djangoproject.com/en/5.2/ref/models/fields/#booleanfield>`_
 and provides additional functionality for handling choices with a fallback
 value.
 
@@ -45,7 +45,7 @@ between enabled and disabled options.
 -------------------------------------------------
 
 This field extends Django's `CharField
-<https://docs.djangoproject.com/en/4.2/ref/models/fields/#charfield>`_ and
+<https://docs.djangoproject.com/en/5.2/ref/models/fields/#charfield>`_ and
 provides additional functionality for handling choices with a fallback
 value.
 
@@ -73,7 +73,7 @@ value.
 -------------------------------------------
 
 This field extends Django's `CharField
-<https://docs.djangoproject.com/en/4.2/ref/models/fields/#charfield>`_ and
+<https://docs.djangoproject.com/en/5.2/ref/models/fields/#charfield>`_ and
 provides additional functionality for handling text fields with a fallback
 value.
 
@@ -96,7 +96,7 @@ value.
 ------------------------------------------
 
 This field extends Django's `URLField
-<https://docs.djangoproject.com/en/4.2/ref/models/fields/#urlfield>`_ and
+<https://docs.djangoproject.com/en/5.2/ref/models/fields/#urlfield>`_ and
 provides additional functionality for handling URL fields with a fallback
 value.
 
@@ -119,7 +119,7 @@ value.
 -------------------------------------------
 
 This extends Django's `TextField
-<https://docs.djangoproject.com/en/4.2/ref/models/fields/#django.db.models.TextField>`_
+<https://docs.djangoproject.com/en/5.2/ref/models/fields/#django.db.models.TextField>`_
 and provides additional functionality for handling text fields with a
 fallback value.
 
@@ -142,7 +142,7 @@ fallback value.
 ------------------------------------------------------
 
 This extends Django's `PositiveIntegerField
-<https://docs.djangoproject.com/en/4.2/ref/models/fields/#positiveintegerfield>`_
+<https://docs.djangoproject.com/en/5.2/ref/models/fields/#positiveintegerfield>`_
 and provides additional functionality for handling positive integer fields
 with a fallback value.
 
@@ -164,7 +164,7 @@ with a fallback value.
 ----------------------------------------------
 
 This extends Django's `DecimalField
-<https://docs.djangoproject.com/en/4.2/ref/models/fields/#decimalfield>`_
+<https://docs.djangoproject.com/en/5.2/ref/models/fields/#decimalfield>`_
 and provides additional functionality for handling decimal fields with a
 fallback value.
 

docs/developer/test-utilities.rst

@@ -37,7 +37,7 @@ Usage example as a context-manager:
     :align: center
 
 This class extends the `default test runner provided by Django
-<https://docs.djangoproject.com/en/4.2/ref/settings/#std:setting-TEST_RUNNER>`_
+<https://docs.djangoproject.com/en/5.2/ref/settings/#std:setting-TEST_RUNNER>`_
 and logs the time spent by each test, making it easier to spot slow tests
 by highlighting time taken by it in yellow (time shall be highlighted in
 red if it crosses the second threshold).
@@ -152,7 +152,7 @@ Example usage:
 -----------------------------------------------------
 
 This mixin overrides the `assertNumQueries
-<https://docs.djangoproject.com/en/4.2/topics/testing/tools/#django.test.TransactionTestCase.assertNumQueries>`_
+<https://docs.djangoproject.com/en/5.2/topics/testing/tools/#django.test.TransactionTestCase.assertNumQueries>`_
 assertion from the django test case to run in a ``subTest`` so that the
 query check does not block the whole test if it fails.