DisableTwoFactorAuthentication should always set `two_factor_confir…

…med_at` to `null` when it has a value

fixes #588

src/Actions/DisableTwoFactorAuthentication.php

@@ -21,7 +21,7 @@ public function __invoke($user)
             $user->forceFill([
                 'two_factor_secret' => null,
                 'two_factor_recovery_codes' => null,
-            ] + (Fortify::confirmsTwoFactorAuthentication() ? [
+            ] + (Fortify::confirmsTwoFactorAuthentication() || ! is_null($user->two_factor_confirmed_at) ? [
                 'two_factor_confirmed_at' => null,
             ] : []))->save();