fix(client): export getCsrfToken directly to support Webpack 5

Fixes `Attempted import error: 'getCsrfToken' is not exported from 'next-auth/client' (imported as 'getCsrfToken’).`-error.

src/client/index.js

@@ -145,7 +145,7 @@ export async function getSession (ctx) {
   return session
 }
 
-async function getCsrfToken (ctx) {
+export async function getCsrfToken (ctx) {
   return (await _fetchData('csrf', ctx))?.csrfToken
 }