fix: update create-plugin command

https://web.tracklify.com/project/2b7ZVgE5/AdminForth/1238/X7lSumpP/when-create-plugin-now-is-crea

Author: yaroslav8765

adminforth/commands/createPlugin/templates/index.ts.hbs

@@ -9,6 +9,7 @@ export default class {{pluginName}} extends AdminForthPlugin {
   constructor(options: PluginOptions) {
     super(options, import.meta.url);
     this.options = options;
+    this.shouldHaveSingleInstancePerWholeApp = () => false;
   }
 
   async modifyResourceConfig(adminforth: IAdminForth, resourceConfig: AdminForthResource) {
@@ -27,10 +28,6 @@ export default class {{pluginName}} extends AdminForthPlugin {
     return `single`;
   }
 
-  shouldHaveSingleInstancePerWholeApp(): boolean {
-    return false;
-  }
-
   setupEndpoints(server: IHttpServer) {
     server.endpoint({
       method: 'POST',