Update the copyright date to 2023 in the about dialog (#6679)

Author: jtpio

packages/help-extension/src/index.tsx

@@ -149,7 +149,7 @@ const plugin: JupyterFrontEndPlugin<void> = {
           </span>
         );
         const version = trans.__('Version: %1', app.version);
-        const copyright = trans.__('© 2021-2022 Jupyter Notebook Contributors');
+        const copyright = trans.__('© 2021-2023 Jupyter Notebook Contributors');
         const body = (
           <>
             <span className="jp-AboutNotebook-version">{version}</span>