refactor - check F841 (PL^5202)

(cherry picked from commit 94d5b043ff701bd1bc88e36691ea1667ed894ea6)

tests/metrics/classification/test_confusion_matrix.py

@@ -130,4 +130,4 @@ def test_warning_on_nan(tmpdir):
     target = torch.randint(3, size=(20,))
 
     with pytest.warns(UserWarning, match='.* nan values found in confusion matrix have been replaced with zeros.'):
-        confmat = confusion_matrix(preds, target, num_classes=5, normalize='true')
+        confusion_matrix(preds, target, num_classes=5, normalize='true')

tests/metrics/test_metric.py

@@ -27,7 +27,7 @@ class Dummy(Metric):
 
 
 def test_inherit():
-    a = Dummy()
+    Dummy()
 
 
 def test_add_state():