Simplify comparison

Author: Zeroto521

src/pyscipopt/expr.pxi

@@ -382,9 +382,7 @@ cdef class ProdExpr(FuncExpr):
 
     def __add__(self, other):
         other = Expr.to_const_or_var(other)
-        if isinstance(other, ProdExpr) and hash(frozenset(self)) == hash(
-            frozenset(other)
-        ):
+        if isinstance(other, ProdExpr) and hash(self) == hash(other):
             return ProdExpr(*self, coef=self.coef + other.coef)
         return super().__add__(other)