我只是想创建一个新的laravel项目，面对这个信息

Creating a "laravel/laravel" project at "./example-app"
Installing laravel/laravel (v8.5.22)
  - Installing laravel/laravel (v8.5.22): Extracting archive
Created project in /home/alifirhas/0_Work/Belajar/postgresql/example-app
> @php -r "file_exists('.env') || copy('.env.example', '.env');"
Loading composer repositories with package information
Updating dependencies
Your requirements could not be resolved to an installable set of packages.

  Problem 1
    - laravel/framework[v8.40.0, ..., 8.x-dev] require ext-mbstring * -> it is missing from your system. Install or enable PHP's mbstring extension.
    - Root composer.json requires laravel/framework ^8.40 -> satisfiable by laravel/framework[v8.40.0, ..., 8.x-dev].

To enable extensions, verify that they are enabled in your .ini files:
    - /etc/php/8.0/cli/php.ini
    - /etc/php/8.0/cli/conf.d/10-opcache.ini
    - /etc/php/8.0/cli/conf.d/10-pdo.ini
    - /etc/php/8.0/cli/conf.d/20-calendar.ini
    - /etc/php/8.0/cli/conf.d/20-ctype.ini
    - /etc/php/8.0/cli/conf.d/20-exif.ini
    - /etc/php/8.0/cli/conf.d/20-ffi.ini
    - /etc/php/8.0/cli/conf.d/20-fileinfo.ini
    - /etc/php/8.0/cli/conf.d/20-ftp.ini
    - /etc/php/8.0/cli/conf.d/20-gettext.ini
    - /etc/php/8.0/cli/conf.d/20-iconv.ini
    - /etc/php/8.0/cli/conf.d/20-phar.ini
    - /etc/php/8.0/cli/conf.d/20-posix.ini
    - /etc/php/8.0/cli/conf.d/20-readline.ini
    - /etc/php/8.0/cli/conf.d/20-shmop.ini
    - /etc/php/8.0/cli/conf.d/20-sockets.ini
    - /etc/php/8.0/cli/conf.d/20-sysvmsg.ini
    - /etc/php/8.0/cli/conf.d/20-sysvsem.ini
    - /etc/php/8.0/cli/conf.d/20-sysvshm.ini
    - /etc/php/8.0/cli/conf.d/20-tokenizer.ini
You can also run `php --ini` inside terminal to see which files are used by PHP in CLI mode.

看起来我必须在我的计算机上安装php mbstring，所以我运行了这个命令

sudo apt-get install php-mbstring

正如我在这个线程中发现的：laravel/framework需要ext-mbstring
但还有另一个错误消息

Reading package lists... Done
Building dependency tree       
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 php-mbstring : Depends: php8.0-mbstring but it is not going to be installed
E: Unable to correct problems, you have held broken packages.

这是我运行时的错误代码 sudo apt install php7.4-mbstring ```
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
php7.4-mbstring : Depends: libonig5 (>= 6.8.1) but it is not installable
E: Unable to correct problems, you have held broken packages.

### 我试过什么

在我的计算机上重新安装php7.4，然后尝试安装mbstring，但失败
将我的php版本更新到版本8，然后尝试安装mbstring，但失败
执行此线程中的操作：https://askubuntu.com/questions/1064634/unable-to-install-php-mbstring，但失败了
那么，有人知道如何安装php mbstring吗？或者我怎样才能做一个laravel项目？
我希望你们能帮我解决这个问题。我已经研究这个问题将近8个小时了，仍然找不到解决办法。