Make pyinstaller spec more generic

[JWCook]

          Thanks. I tried to get this working without your naturtag-installer.exe for the new tagged version and I couldn't make it work. I tried the steps in packaging/build-win.ps1 and ultimately could not invoke pyinstaller due to these errors:

pyinstaller -y packaging\naturtag.spec
545 INFO: PyInstaller: 6.11.1, contrib hooks: 2024.11
546 INFO: Python: 3.12.5
591 INFO: Platform: Windows-10-10.0.19045-SP0
591 INFO: Python environment: C:\Users\syner\.pyenv\pyenv-win\versions\3.12.5
606 INFO: Module search paths (PYTHONPATH):
['C:\\Users\\syner\\.pyenv\\pyenv-win\\versions\\3.12.5\\Scripts\\pyinstaller.exe',
 'C:\\Users\\syner\\.pyenv\\pyenv-win\\versions\\3.12.5\\python312.zip',
 'C:\\Users\\syner\\.pyenv\\pyenv-win\\versions\\3.12.5\\DLLs',
 'C:\\Users\\syner\\.pyenv\\pyenv-win\\versions\\3.12.5\\Lib',
 'C:\\Users\\syner\\.pyenv\\pyenv-win\\versions\\3.12.5',
 'C:\\Users\\syner\\AppData\\Roaming\\Python\\Python312\\site-packages',
 'C:\\Users\\syner\\.pyenv\\pyenv-win\\versions\\3.12.5\\Lib\\site-packages',
 'C:\\Users\\syner\\.pyenv\\pyenv-win\\versions\\3.12.5\\Lib\\site-packages\\setuptools\\_vendor',
 'C:\\Users\\syner\\work\\naturtag',
 'C:\\Users\\syner\\work\\naturtag']
1667 INFO: Appending 'binaries' from .spec
Unable to find 'C:\\Users\\syner\\.virtualenvs\\naturtag\\Lib\\site-packages\\pyexiv2\\lib\\exiv2.dll' when adding binary and data files.

Apparently I need build tools from Microsoft to make that work, for which I currently do not have the space on my system. I could move things around to liberate some space but wanted to at least touch base with you here first to confirm I'm on the right track.

Originally posted by @synrg in #210 (comment)

[JWCook]

At minimum, it needs to dynamically detect the current site-packages dir. Example one-liner:

python -c "from distutils.sysconfig import get_python_lib; print(get_python_lib())"