Fix Makefile

Makefile

@@ -25,7 +25,7 @@ requirements:
 requirements-test:
 	@echo "Installing ${PACKAGE_NAME} tests requirements..."
 	@make requirements
-	pip install -r requirements-test.txt
+	pip install -r requirements-tests.txt
 
 requirements-docs:
 	@echo "Installing ${PACKAGE_NAME} docs requirements..."