feat(signals): remove union type from models

Author: rainerhahnekamp

modules/signals/src/signal-store-models.ts

@@ -11,9 +11,9 @@ export type StateSignals<State> = IsKnownRecord<Prettify<State>> extends true
     }
   : {};
 
-export type SignalsDictionary = Record<string | symbol, Signal<unknown>>;
+export type SignalsDictionary = Record<string, Signal<unknown>>;
 
-export type MethodsDictionary = Record<string | symbol, Function>;
+export type MethodsDictionary = Record<string, Function>;
 
 export type SignalStoreHooks = {
   onInit?: () => void;