speccpu/x264: fix importlib deprecation warning

src/speccpu/x264.py

@@ -13,7 +13,7 @@ class MCBuilder:
     @staticmethod
     def get_src():
         assert __package__ is not None
-        with importlib.resources.open_text(__package__, "mc.c") as f:
+        with (importlib.resources.files(__package__) / "mc.c").open("r") as f:
             mc_src = f.read()
         return mc_src