Update @types/showdown requirement from 1.9.0 to 1.9.1

This reverts commit d7af18ef.

Updates the requirements on [terser-webpack-plugin](https://github.com/webpack-contrib/terser-webpack-plugin) to permit the latest version.
- [Release notes](https://github.com/webpack-contrib/terser-webpack-plugin/releases)
- [Changelog](https://github.com/webpack-contrib/terser-webpack-plugin/blob/master/CHANGELOG.md)
- [Commits](https://github.com/webpack-contrib/terser-webpack-plugin/commits/v1.2.1

)

Signed-off-by: dependabot[bot] <support@dependabot.com>

* 管理者がサインイン履歴を参照できるツール

* remove debug code

* Toggle show/hide password

* hoverでアンダーラインが中途半端に出てダサいので出さないように

* Update signin.vue

Updates the requirements on [@types/showdown](https://github.com/DefinitelyTyped/DefinitelyTyped) to permit the latest version.
- [Release notes](https://github.com/DefinitelyTyped/DefinitelyTyped/releases)
- [Commits](https://github.com/DefinitelyTyped/DefinitelyTyped/commits

)

Signed-off-by: dependabot[bot] <support@dependabot.com>

* Update notifications.ts

* Update notifications.ts

* Update notifications.ts

* Update notifications.ts

* Add missing semicolon

* Improve readability

* Fix typo

New Crowdin translations