fix: Update Django Official Link to drop 2.2 and support 4.2 (#903)

Co-authored-by: Knut Olav Løite <koloite@gmail.com>

Author: mitsuo0114

packages/django-google-spanner/README.rst

@@ -41,9 +41,9 @@ In order to use this library, you first need to go through the following steps:
 .. _Setup Authentication.: https://googleapis.dev/python/google-api-core/latest/auth.html
 
 This package provides a `3rd-party database backend
-<https://docs.djangoproject.com/en/2.2/ref/databases/#using-a-3rd-party-database-backend>`__
+<https://docs.djangoproject.com/en/4.2/ref/databases/#using-a-3rd-party-database-backend>`__
 for using `Cloud Spanner <https://cloud.google.com/spanner>`__ with the `Django
-ORM <https://docs.djangoproject.com/en/2.2/topics/db/>`__. It uses the `Cloud
+ORM <https://docs.djangoproject.com/en/4.2/topics/db/>`__. It uses the `Cloud
 Spanner Python client library <https://github.com/googleapis/python-spanner>`__
 under the hood.
 
@@ -64,9 +64,9 @@ dependencies.
 Supported versions
 ~~~~~~~~~~~~~~~~~~
 
-The library supports `Django 2.2
-<https://docs.djangoproject.com/en/2.2/>`_, and `Django 3.2
-<https://docs.djangoproject.com/en/3.2/>`_.
+The library supports `Django 3.2
+<https://docs.djangoproject.com/en/3.2/>`_, and `Django 4.2
+<https://docs.djangoproject.com/en/4.2/>`_.
 Both versions are long-term support (LTS) releases for the
 `Django project<https://www.djangoproject.com/download/#supported-versions>_`.
 The minimum required Python version is 3.6.
@@ -209,7 +209,7 @@ Then visit http://127.0.0.1:8000/admin/
 Create and register your first model
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-Please follow the guides in https://docs.djangoproject.com/en/2.2/intro/tutorial02/#creating-models
+Please follow the guides in https://docs.djangoproject.com/en/4.2/intro/tutorial02/#creating-models
 to create and register the model to the Django’s automatically-generated admin site.
 
 How it works