Fix inheritance of special math function enum classes

src/pystencils/backend/functions.py

@@ -94,7 +94,7 @@ class MathFunctions(Enum):
         self.num_args = num_args
 
 
-class NumericLimitsFunctions(MathFunctions):
+class NumericLimitsFunctions(Enum):
     """Numerical limits functions supported by the backend.
 
     Each platform has to materialize these functions to a concrete implementation.
@@ -109,12 +109,12 @@ class PsMathFunction(PsFunction):
 
     __match_args__ = ("func",)
 
-    def __init__(self, func: MathFunctions) -> None:
+    def __init__(self, func: MathFunctions | NumericLimitsFunctions) -> None:
         super().__init__(func.function_name, func.num_args)
         self._func = func
 
     @property
-    def func(self) -> MathFunctions:
+    def func(self) -> MathFunctions | NumericLimitsFunctions:
         return self._func
 
     def __str__(self) -> str: