Remove test code that does not exercise anything in pybind11, but breaks...

Remove test code that does not exercise anything in pybind11, but breaks between Python 3.12alpha3 (still working) and 3.12alpha6 (broken): (#4559)

```
str(OrderedDict([(1, "a"), (2, "b")]))
```

Old:
```
OrderedDict([(1, 'a'), (2, 'b')])
```

New:
```
OrderedDict({1: 'a', 2: 'b'})
```

See also: https://github.com/python/cpython/issues/101446