stabilize example/pythonlib/testing/2-test-deps (#4466)

Seems sometimes the `ok` gets printed on a separate line (e.g. here
https://github.com/com-lihaoyi/mill/actions/runs/13125384248/job/36620838982)
so adjust the assert to accept that

Author: lihaoyi

example/pythonlib/testing/2-test-deps/build.mill

@@ -49,13 +49,15 @@ object bar extends PythonModule {
 
 > ./mill foo.test
 ...Using BarTestUtils.bar_assert_equals...
-...test_equal_string (test.TestScript...)...ok...
+...test_equal_string (test.TestScript...)...
+...ok...
 ...Ran 1 test...
 ...OK...
 
 > ./mill bar.test
 ...Using BarTestUtils.bar_assert_equals...
-...test_mean (test.TestScript...)...ok...
+...test_mean (test.TestScript...)...
+...ok...
 ...Ran 1 test...
 ...OK...