Added __int__ to IFDRational for Python >= 3.11

[radarhere]

In Python 3.11, the following code

from PIL.TiffImagePlugin import IFDRational
ifd = IFDRational(1)
int(ifd)

gives

DeprecationWarning: The delegation of int() to __trunc__ is deprecated.
  int(ifd)

I noticed the deprecation warning in https://github.com/python-pillow/Pillow/actions/runs/4342791039/jobs/7584046826#step:8:4230

This deprecation was added in python/cpython#89140

This PR fixes the matter by adding __int__ to IFDRational - but only for Python >= 3.11. Below Python 3.11, this change gives

AttributeError: 'Fraction' object has no attribute '__int__'. Did you mean: '__init__'?