fix(test): replace yield with do_something() in correct_while8 fixture

yield is only valid inside a function; the test fixture string was
causing a SyntaxError when compiled at module level. The intent of
the test case (while True inside try/except with nesting) is preserved.

Author: User

tests/test_visitors/test_ast/test_loops/test_loops/test_infinite_while_loops.py

@@ -111,7 +111,7 @@ async def worker():
 try:
     if some:
         while True:
-            yield some
+            do_something()
 except StopIteration:
     pass
 """