Update inline_lifts.py

Author: nfarabullini

src/gt4py/next/iterator/transforms/inline_lifts.py

@@ -140,8 +140,7 @@ class Flag(enum.IntEnum):
         #: when we see that it is not required.
         INLINE_LIFTED_ARGS = 16
 
-    def predicate(self, _1, _2):
-        return True
+    predicate: Callable[[ir.Expr, bool], bool] = lambda _1, _2: True
 
     flags: int = (
         Flag.PROPAGATE_SHIFT