Your requirements could not be resolved to an installable set of packages. 解決方法

経緯

以下の手順でエラーが発生しました。

$ composer install
Installing dependencies from lock file (including require-dev)
Verifying lock file contents can be installed on current platform.
Your lock file does not contain a compatible set of packages. Please run composer update.

Problem 1
    - asm89/stack-cors is locked to version v2.0.1 and an update of this package was not requested.
    - asm89/stack-cors v2.0.1 requires php ^7.0 -> your php version (8.1.2) does not satisfy that requirement.
   
・
・
・

とりあえずメッセージの通りcomposer updateしてみる。

$ composer update
Loading composer repositories with package information
Info from https://repo.packagist.org: #StandWithUkraine
Updating dependencies
Your requirements could not be resolved to an installable set of packages.

  Problem 1
    - Root composer.json requires php ^7.3 but your php version (8.1.2) does not satisfy that requirement.

composer updateもできませんでした。。
どうやらphp7.3が必要なのにphp8を使っていることが原因のようです！

解決

以下のように、composer.jsonにphpバージョン8を追加してあげます！
これでphp8でコマンド実行してもエラーは出なくなります!

"require": {
    "php": "^7.3",
},

↓ //8.0を追加

"require": {
    "php": "^7.3|^8.0",
},

再度composer updateからinstallまで実行

$ composer update
・
・
・
Package manifest generated successfully.
77 packages you are using are looking for funding.
Use the `composer fund` command to find out more!

$ composer install
・
・
・
Package manifest generated successfully.
77 packages you are using are looking for funding.
Use the `composer fund` command to find out more!

これで無事成功です！

参考記事