feat: add help target and set as default goal

Makefile

@@ -1,4 +1,6 @@
-test-requirements:
+.DEFAULT_GOAL := help
+
+test-requirements: ## Install test requirements
 	pip install black mypy pylint pyyaml types-PyYAML
 
 test: test-lint test-unit test-types test-format ## Run all tests by decreasing order of priority
@@ -17,3 +19,9 @@ test-types: ## Check type definitions
 
 format: ## Format code
 	black *.py
+
+ESCAPE = 
+help: ## Print this help
+	@grep -E '^([a-zA-Z_-]+:.*?## .*|######* .+)$$' Makefile \
+		| sed 's/######* \(.*\)/@               $(ESCAPE)[1;31m\1$(ESCAPE)[0m/g' | tr '@' '\n' \
+		| awk 'BEGIN {FS = ":.*?## "}; {printf "\033[33m%-30s\033[0m %s\n", $$1, $$2}'