Revert "fix(test): guard pyximport import for non-Cython tox envs"

This reverts commit 6cde4f2.

Author: keyz182

tests/unit/wiring/conftest.py

@@ -1,12 +1,5 @@
-"""Enable on-import compilation of the .pyx wiring fixture via pyximport.
+"""Enable on-import compilation of the .pyx wiring fixture via pyximport."""
 
-Cython is not installed in every tox env (e.g. pydantic-{v1,v2}), so the
-import is guarded — test_cython.py skips at importorskip in that case.
-"""
+import pyximport
 
-try:
-    import pyximport
-
-    pyximport.install(language_level=3)
-except ImportError:
-    pass
+pyximport.install(language_level=3)