This will fix #23 .
This will also remove the blocker to python >= 3.12.

Since we are moving to a different building system some things have changed, most notably:

• the recursive building configuration is now back
• the script in bin/qbindiff has been moved to src/qbindiff/__main__.py as per standard

Also I took the chance to get rid of the deprecated IF-ELSE operator (aka conditional compilation) in cython