build: replace Django unittest runner with pytest

Pytest understands unittest-styled tests, so there is no immediate
need to update the test files themselves to a pytest idiomatic
syntax.

Fixes: GREG-14

Makefile

+DJANGO_SETTINGS_MODULE ?= gregsite.settings.dev
+
 BLACK ?= black -q
 MYPY ?= mypy
 PIP ?= pip -q
 POETRY ?= poetry
 PYLINT ?= pylint -sn
+PYTEST ?= pytest -v -s --no-header
 PYTHON ?= python3.9
 VENV ?= venv
 
 mypy = $(MYPY) --config-file mypy.ini
 pip = python -m $(PIP)
 poetry = python -m $(POETRY)
+pytest = DJANGO_SETTINGS_MODULE=$(DJANGO_SETTINGS_MODULE) python -m $(PYTEST)
 venv = . $(VENV)/bin/activate &&
 
 PACKAGES = greg/ gregsite/
@@ -30,7 +34,7 @@ $(VENV)/touchfile:
 .PHONY: test
 test: $(VENV)
 	$(venv) $(mypy) -p greg
-	$(venv) python manage.py test
+	$(venv) $(pytest)
 
 .PHONY: lint
 lint: $(VENV)

pyproject.toml

@@ -28,6 +28,7 @@ ipython = "*"
 mypy = "*"
 pylint = "*"
 pylint-django = "*"
+pytest-django = "^4.4.0"
 rope = "*"
 
 [tool.black]