Bump django to version 4 LTS

Apparently version 3 is EOL.

Fixes #173

requirements.in/base.txt

@@ -1,4 +1,4 @@
-django<4.0
+django>=4.0<5.0
 msgpack
 pynacl
 fastapi

requirements.txt

@@ -1,5 +1,5 @@
 #
-# This file is autogenerated by pip-compile with Python 3.11
+# This file is autogenerated by pip-compile with Python 3.12
 # by the following command:
 #
 #    pip-compile --output-file=requirements.txt requirements.in/base.txt
@@ -18,7 +18,7 @@ cffi==1.15.1
     # via pynacl
 click==8.1.3
     # via uvicorn
-django==3.2.16
+django==4.1.13
     # via -r requirements.in/base.txt
 fastapi==0.88.0
     # via -r requirements.in/base.txt
@@ -38,8 +38,6 @@ pynacl==1.5.0
     # via -r requirements.in/base.txt
 python-dotenv==0.21.0
     # via uvicorn
-pytz==2022.6
-    # via django
 pyyaml==6.0.1
     # via uvicorn
 redis==4.4.0