test: add type hints

Author: remarkablemark

tests/test_template.py

@@ -1,9 +1,9 @@
 from python_package_template import hello
 
 
-def test_hello():
+def test_hello() -> None:
     assert hello() == "Hello, World!"
 
 
-def test_hello_world():
+def test_hello_world() -> None:
     assert hello("world") == "Hello, world!"