fix lint and static type check

src/pystencils/backend/symbols.py

@@ -49,7 +49,7 @@ class PsSymbol:
 
     def __eq__(self, other: object) -> bool:
         return (
-            type(self) == type(other)
+            isinstance(other, PsSymbol)
             and self._name == other._name
             and self._dtype == other._dtype
         )