DEBUG: explicitly upgrade Django to 5.1.x

b/c Kiwi TCMS still requires Django 5.0.x and we want to test with newer
version

Makefile

@@ -24,6 +24,9 @@ test:
 	    git clone --depth 1 https://github.com/kiwitcms/Kiwi.git $(KIWI_INCLUDE_PATH); \
 	    pip install -U -r $(KIWI_INCLUDE_PATH)/requirements/base.txt; \
 	fi
+
+	# explicitly upgrade Django to 5.1.x
+	pip install -U Django
 
 	PYTHONPATH=.:$(KIWI_INCLUDE_PATH) EXECUTOR=standard PYTHONWARNINGS=d AUTO_CREATE_SCHEMA='' \
         KIWI_TENANTS_DOMAIN='test.com' \