Upgrade to Django 3.2 LTS

Step 1 of the upgrade (Python 3.9). Dependencies are bumped to their
newest versions compatible with Django 3.2.

DEFAULT_AUTO_FIELD is set to AutoField, which matches the existing
tables, so no migration is needed and the W042 warnings go away.

dal/settings.py

@@ -150,6 +150,9 @@ DATABASES = {
 }
 SECRET_KEY = config('SECRET_KEY')
 
+# Keep 32-bit ids: existing tables were created with AutoField.
+DEFAULT_AUTO_FIELD = 'django.db.models.AutoField'
+
 AUTH_LDAP_USER_ATTR_MAP = {
     "first_name": "givenName",
     "last_name": "sn",

requirements.txt

@@ -1,10 +1,10 @@
-# Baseline: what production runs (Django 2.2), pinned so the upgrade is reproducible.
-django==2.2.28
-django-auth-ldap==2.2.0
-python-ldap==3.4.4
-django-bootstrap3==14.2.0
+# Upgrade step 1: Django 3.2 LTS on Python 3.9.
+django==3.2.25
+django-auth-ldap==4.8.0
+python-ldap==3.4.8
+django-bootstrap3==23.6
 python-decouple==3.8
 ldap3==2.9.1
-djangorestframework==3.12.4
-pyotp==2.9.0
-requests==2.32.3
+djangorestframework==3.15.1
+pyotp==2.10.0
+requests==2.32.5