Update index.d.ts

Fixed #15780

Author: I-Enderlord-I

types/index.d.ts

@@ -622,9 +622,8 @@ declare module 'mongoose' {
     set<K extends keyof SchemaOptions>(key: K, value: SchemaOptions<DocType>[K], _tags?: any): this;
 
     /** Adds static "class" methods to Models compiled from this schema. */
-    static<K extends keyof TStaticMethods>(name: K, fn: TStaticMethods[K]): this;
-    static(obj: { [F in keyof TStaticMethods]: TStaticMethods[F] }): this;
-    static(obj: { [F in keyof TStaticMethods]: TStaticMethods[F] } & { [name: string]: (this: TModelType, ...args: any[]) => any }): this;
+    static<K extends keyof TStaticMethods>(name: K, fn: TStaticMethods[K] & ((this: TModelType, ...args: any[]) => any)): this;
+    static(obj: Partial<TStaticMethods> & { [name: string]: (this: TModelType, ...args: any[]) => any }): this;
     static(name: string, fn: (this: TModelType, ...args: any[]) => any): this;
 
     /** Object of currently defined statics on this schema. */