Fix various build issues

[AlexanderViand]

Modern setups (e.g., ubuntu 24.04) weren't able to build Pyfhel successfully anymore because of a few issues

• the SEAL version we used had a dependency asking for cmake <3.5 compatibility which modern cmake no longer supports -> updated to most recent SEAL version
• Python3.12 deprecated a few things and we had numpy/setuptools dependencies that were still using them -> bump numpy/setuptools version
• There was also a minor bug in PyPoly.pyx - no idea why that hadn't popped up earlier, as it shouldn't have worked even on older setups...

This should fix #257, #256

[codecov-commenter]

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Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.80%. Comparing base (e8788d1) to head (324c726).
⚠️ Report is 10 commits behind head on master.
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Additional details and impacted files

@@           Coverage Diff           @@
##           master     #261   +/-   ##
=======================================
  Coverage   98.80%   98.80%           
=======================================
  Files           3        3           
  Lines        1004     1005    +1     
=======================================
+ Hits          992      993    +1     
  Misses         12       12           

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[AlexanderViand]

I can't get the macOS CI to work and since I don't have a macOS device on hand, I'm going to have to give up on that for the moment. Maybe @ibarrond or someone else with a macOS device can let me know if pip install . works locally (i.e., if it's purely a CI issue, or if the build is actually broken on macOS)

[ibarrond]

Merging these changes and pushing a new version to PyPI. The MacOS build will remain broken for now (although #263 might solve it)