fix type

packages/backend/src/server/api/SigninApiService.ts

 import { randomBytes } from 'node:crypto';
 import { Inject, Injectable } from '@nestjs/common';
 import bcrypt from 'bcryptjs';
-import * as OTPAuth from "otpauth";
+import * as OTPAuth from 'otpauth';
 import { IsNull } from 'typeorm';
 import { DI } from '@/di-symbols.js';
 import type { UserSecurityKeysRepository, SigninsRepository, UserProfilesRepository, AttestationChallengesRepository, UsersRepository } from '@/models/index.js';
@@ -156,7 +156,7 @@ export class SigninApiService {
 			}
 
 			const delta = OTPAuth.TOTP.validate({
-				secret: OTPAuth.Secret.fromBase32(profile.twoFactorSecret),
+				secret: OTPAuth.Secret.fromBase32(profile.twoFactorSecret!),
 				digits: 6,
 				token,
 				window: 1,