Add 'contains' validation error message in Japanese translation

[nshiro]

contains エラーメッセージを追加しました☕

元はこちらです。
https://github.com/laravel/framework/pull/51348/files
laravel/framework@2f8b95a

[what-the-diff]

PR Summary

• Enhancement to validation.php in Japanese Translations
  A new validation rule called contains was introduced to the Japanese language version of validation.php. This enhancement enriches the existing set of validation rules, enabling more precise data checks and thus improving the overall application accuracy when dealing with Japanese inputs.

[askdkc]

@nshiro さん

ありがとうございます〜💕