test(content): accept platform-owned SWIG module labels

Linux's SWIG runtime already labels PyMuPDF helper types as
swig_runtime_data5; macOS leaves them unset and the compatibility shim
supplies pymupdf._mupdf. The invariant is non-null __module__, not one
platform-specific fallback string.

Verified: content splitter 21 passed on the clean worktree.

Author: NetDevAutomate

packages/studyloop/tests/test_content_splitter.py

@@ -18,7 +18,7 @@ def test_pymupdf_swig_types_are_labelled_for_python_313() -> None:
         for value in vars(module).values():
             swig_type = type(value)
             if swig_type.__name__ in {"SwigPyPacked", "SwigPyObject", "swigvarlink"}:
-                assert swig_type.__module__ == "pymupdf._mupdf"
+                assert swig_type.__module__ is not None
 
 
 @pytest.fixture