implement testBrokenMethod() at WasRun

This implementation will support the code being executed as part of TestCase.testFailedResult. For now, though, we're just raising an exception.

Checklist:
- Invoke tearDown even if the test method fails
- Run multiple tests
- Report collected results ✅

---

Output:
➜ python3 src/test_case_test.py
Traceback (most recent call last):
  File "tdd-xunit-example/src/test_case_test.py", line 18, in <module>
    TestCaseTest("testFailedResult").run()
  File "tdd-xunit-example/src/test_case.py", line 17, in run
    method()
  File "tdd-xunit-example/src/test_case_test.py", line 13, in testFailedResult
    result = test.run()
             ^^^^^^^^^^
  File "tdd-xunit-example/src/test_case.py", line 17, in run
    method()
  File "tdd-xunit-example/src/was_run.py", line 20, in testBrokenMethod
    raise Exception
Exception

src/was_run.py

@@ -15,3 +15,6 @@ def testMethod(self) -> None:
 
     def tearDown(self) -> None:
         self.log = self.log + "tearDown "
+
+    def testBrokenMethod(self) -> None:
+        raise Exception