gh-92886: Fix test in test_routines.py so that it works when running with optimizations (-O)

[jackh-ncl]

#92886

Before:

$ ./python.exe -Om unittest test.test_coroutines

........................./Users/.../dev/cpython/Lib/test/test_coroutines.py:2207: RuntimeWarning: coroutine 'CoroutineTest.test_bpo_45813_2.<locals>.f' was never awaited
  with self.assertWarns(RuntimeWarning):
RuntimeWarning: Enable tracemalloc to get the object allocation traceback
............................................................F.........
======================================================================
FAIL: test_with_5 (test.test_coroutines.CoroutineTest.test_with_5)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/Users/.../dev/cpython/Lib/test/test_coroutines.py", line 1284, in test_with_5
    with self.assertRaises(AssertionError):
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AssertionError: AssertionError not raised

----------------------------------------------------------------------
Ran 95 tests in 0.323s

FAILED (failures=1)

After:

$ ./python.exe -Om unittest test.test_coroutines

........................./Users/jackhindmarch/dev/cpython/Lib/test/test_coroutines.py:2207: RuntimeWarning: coroutine 'CoroutineTest.test_bpo_45813_2.<locals>.f' was never awaited
  with self.assertWarns(RuntimeWarning):
RuntimeWarning: Enable tracemalloc to get the object allocation traceback
......................................................................
----------------------------------------------------------------------
Ran 95 tests in 0.325s

OK

[bedevere-bot]

Most changes to Python require a NEWS entry.

Please add it using the blurb_it web app or the blurb command-line tool.

[kumaraditya303]

News entry is not required, you can remove it.

[jackh-ncl]

News entry is not required, you can remove it.

done

[JelleZijlstra]

@iritkatriel made this same change already in #98060.

[iritkatriel]

Sorry, I didn't see this.