…ule subclasses

This patch relax specialization requirements from
``PyModule_CheckExact(op)`` to
``Py_TYPE(op)->tp_getattro != PyModule_Type.tp_getattro``.

Benchmarks:

```py
import pyperf
import b
import c
runner = pyperf.Runner()
runner.timeit('b.x', 'b.x', globals=globals())
runner.timeit('c.x', 'c.x', globals=globals())
```
```py
x = 1
```
```py
import sys, types
x = 1
class _Foo(types.ModuleType): pass
sys.modules[__name__].__class__ = _Foo
```

On the main:
```
$ python a.py -q
b.x: Mean +- std dev: 50.2 ns +- 2.7 ns
c.x: Mean +- std dev: 132 ns +- 7 ns
```

With the patch:
```
$ python a.py -q
b.x: Mean +- std dev: 52.9 ns +- 3.6 ns
c.x: Mean +- std dev: 52.6 ns +- 2.7 ns
```

Co-authored-by: Nicolas Tessore <n.tessore@ucl.ac.uk>