add no-op tearDown() method at TestCase

Checklist:
- Invoke tearDown afterward ✅
- Invoke tearDown even if the test method fails
- Run multiple tests
- Report collected results
- Log string in WasRun ✅

src/test_case.py

@@ -11,3 +11,6 @@ def run(self) -> None:
         method = getattr(self, self.name)
         method()
         self.tearDown()
+
+    def tearDown(self) -> None:
+        pass