Add Makefile with packaging and publishing helpers

Makefile

@@ -0,0 +1,20 @@
+.PHONY: package-deps package-build package-check package-upload package clean
+
+package-deps:
+	python3 -m pip install --upgrade build
+
+package-build: package-deps
+	python3 -m build
+
+package-check: package-build     ## Check the distribution is valid
+	python3 -m twine check dist/*
+
+package-upload: package-deps package-check
+	python3 -m twine upload dist/* --repository-url https://upload.pypi.org/legacy/
+
+package: package-upload
+
+clean:
+	rm -rf brunnhilde.egg-info/
+	rm -rf build/
+	rm -rf dist/