fix: update return type of subscribe method in SharedValuesManager to a function

Author: HichemTab-tech

src/SharedValuesManager.ts

@@ -283,7 +283,7 @@ export class SharedValuesApi<T extends SharedValue, V, R = T> {
         return all;
     }
 
-    subscribe<S extends string = string>(sharedCreated: SharedCreated, listener: AFunction): void;
+    subscribe<S extends string = string>(sharedCreated: SharedCreated, listener: AFunction): () => void;
     subscribe<S extends string = string>(key: S | SharedCreated, listener: AFunction, scopeName?: Prefix) {
         let keyStr!: string;
         let prefixStr!: string;