build: Explicitly install setuptools in ci.txt

We need setuptools to run tox but it doesn't get install by default in
python environmnets starting with Python 3.12 so explicitly install it
when setting up the CI enviromnent.

Makefile

@@ -111,7 +111,7 @@ upgrade: requirements check_pins ## update the requirements/*.txt files with the
 	$(PIP_COMPILE) --no-emit-trusted-host --no-emit-index-url -o requirements/doc.txt requirements/doc.in
 	$(PIP_COMPILE) --no-emit-trusted-host --no-emit-index-url -o requirements/test.txt requirements/test.in
 	$(PIP_COMPILE) --no-emit-trusted-host --no-emit-index-url -o requirements/dev.txt requirements/dev.in
-	$(PIP_COMPILE) --no-emit-trusted-host --no-emit-index-url -o requirements/ci.txt requirements/ci.in
+	$(PIP_COMPILE) --no-emit-trusted-host --no-emit-index-url --allow-unsafe -o requirements/ci.txt requirements/ci.in
 	$(PIP_COMPILE) --no-emit-trusted-host --no-emit-index-url -o requirements/js_test.txt requirements/js_test.in
 	# This section removes django from test.txt to
 	# let tox control the Django version for tests

requirements/ci.in

@@ -3,3 +3,4 @@
 -c constraints.txt
 
 tox                       # Virtualenv management for tests
+setuptools

requirements/ci.txt

@@ -28,3 +28,7 @@ tox==3.28.0
     #   -r requirements/ci.in
 virtualenv==20.25.3
     # via tox
+
+# The following packages are considered to be unsafe in a requirements file:
+setuptools==69.5.1
+    # via -r requirements/ci.in