fix(curriculum): use output test for bill splitter step 4 print hint (#67444)

curriculum/challenges/english/blocks/workshop-bill-splitter/6982684f3a25f379e195a5fc.md

@@ -43,9 +43,16 @@ You should print the string `Total bill so far:` followed by a space and the val
 ```js
 ({
     test: () => runPython(`
-    sol1 = "print('Total bill so far:', running_total)"
-    sol2 = "print(f'Total bill so far: {running_total}')"
-    assert _Node(_code).has_call(sol1) or _Node(_code).has_call(sol2)`)
+import io, contextlib
+
+_expected = f"Total bill so far: {37.89 + 57.34 + 39.39 + 64.21}"
+
+buffer = io.StringIO()
+with contextlib.redirect_stdout(buffer):
+    exec(_code)
+
+assert _expected in buffer.getvalue()
+`)
 })
 ```