Add test case for assignment expression in `E741.py` (#168)

resources/test/fixtures/E741.py

@@ -70,3 +70,6 @@ try:
     pass
 except ValueError as l:
     pass
+
+if (l := 5) > 0:
+    pass

src/linter.rs

@@ -431,6 +431,11 @@ mod tests {
                 location: Location::new(71, 1),
                 fix: None,
             },
+            Check {
+                kind: CheckKind::AmbiguousVariableName("l".to_string()),
+                location: Location::new(74, 5),
+                fix: None,
+            },
         ];
 
         assert_eq!(actual.len(), expected.len());