fix: correct TypeError test to actually exercise exception handler

The test_measure_time_to_first_review_type_error_path test was passing
but not actually reaching the except TypeError block. The MagicMock
review's submitted_at (a MagicMock, not a datetime) caused
ignore_comment to skip the review as 'pending', so first_review_time
stayed None and the function returned before the TypeError could occur.

Use side_effect to raise TypeError directly from the reviews() call,
which properly exercises the exception handling path.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: zkoppert

test_time_to_first_review.py

@@ -115,10 +115,10 @@ def test_measure_time_to_first_review_ignore_users(self):
     def test_measure_time_to_first_review_type_error_path(self):
         """Test the except TypeError error handling path."""
         mock_issue = MagicMock()
-        mock_issue.created_at = 12345
+        mock_issue.created_at = "2023-01-01T00:00:00Z"
 
         mock_pr = MagicMock()
-        mock_pr.reviews.return_value = [MagicMock()]
+        mock_pr.reviews.side_effect = TypeError("ghost user")
 
         result = measure_time_to_first_review(mock_issue, mock_pr, None, [])
         self.assertIsNone(result)