graphics/py-ueberzug: Fix packaging with Python 3.8+

• Apply the same fix as in 9cb5898561b302d952fec8e2fac66a945a2c4915 by stripping libraries by wildcard paths.

• Also use PYTHONPREFIX_SITELIBDIR instead PYTHON_SITELIBDIR to make the port PREFIX safe while I'm here.

PR: 253815
Approved by: python (with hat)