Py313 fontconfig non linux

[pattems]

fix: use fontconfig font registration on all non-Windows, non-macOS systems

manimpango/_register_font.pyx defines _register_font / _unregister_font under Cython compile-time IF UNAME_SYSNAME == ... branches for Linux, Windows and Darwin only. When building on FreeBSD (and NetBSD, OpenBSD, illumos, ...) none of the branches match, the names are never defined, and import manimpango fails:

ImportError: cannot import name '_register_font' from 'manimpango._register_font'

These systems use fontconfig exactly like Linux, so this makes the fontconfig branch apply to everything except Windows and macOS. Linux, Windows and macOS builds are unchanged. A second, test-only commit gates the two fontconfig-specific unregister tests on the backend rather than on linux.

Testing

Cython 3.0.12 (the <3.1 pin from pyproject.toml), Python 3.13: cythonized _register_font.pyx with compile_time_env={"UNAME_SYSNAME": ...} and listed the module-level names bound in the generated C:

UNAME_SYSNAME	before	after
Linux	_register_font, _unregister_font set	same
Windows, Darwin	_register_font, _unregister_font set	same
FreeBSD, NetBSD	only _fc_register_font/_fc_unregister_font	_register_font, _unregister_font set

Full build of main on FreeBSD 15.1, Python 3.12, 3.13 and 3.14 (pip install from the checkout, pango/cairo/fontconfig from packages):

• before: manimpango.register_font(...) fails with the ImportError above
• after: register_font(DejaVuSans.ttf) returns True and list_fonts() finds it

The second commit is test-only. test_fail_just_unregister is skipped on Linux because fontconfig's unregister_font() always returns True, and test_both_fc_and_register_font_are_same runs only on Linux. Both depend on the fontconfig backend rather than on Linux. On FreeBSD the first test ran and failed (3 cases), and the second never ran. The commit adds a FONTCONFIG flag (neither win32 nor darwin) and uses it in those two skip conditions only. Skips are unchanged on Linux, Windows and macOS.

With both commits (in-place build) on FreeBSD 15.1, pytest -q tests -k font gives 19 passed, 3 skipped (test_fail_just_unregister), 0 failed on Python 3.12, 3.13 and 3.14.

Context

Found while testing packages against Python 3.13 for FreeBSD ports (https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=292105).

[PhilippImhof]

LGTM, thanks

[naveen521kk]

LGTM, thanks! I'll do a patch release with these changes later this week.