comporser 　エラーコード通りバージョンを合わせても同じエラーが出る原因が知りたい

提示コードですが以下のコンソールのエラーの対処方法がわかりません。エラコードrequires nesbot/carbon 2.0.0-beta.2 as 1.25.0 にあるとおり1.25.0にバージョンを合わせたのですが同じエラー出ます。原因がわかりません。
ルートcomposer.jsonにはkylekatarnls/laravel-carbon-20.1.0が必要ですとありますがそれは既にjsonファイルに追加済みですなぜでしょうか？また"nesbot/carbon": "2.0.0-beta.2"としてみましたが別のエラー出ますがこれは正しいのでしょうか？

参考サイト：https://packagist.org/packages/nesbot/carbon#1.25.0
参考サイト：https://packagist.org/packages/kylekatarnls/laravel-carbon-2#0.1.0

json
1{
2    "config": 
3    {
4        "platform-check": false,
5        "platform": {
6            "php": "7.1.8"
7        },
8        "allow-plugins": {
9            "kylekatarnls/update-helper": true
10        }
11    },
12
13    "require": 
14    {
15	"nesbot/carbon": "1.25.0",
16	"kylekatarnls/laravel-carbon-2": "0.1.0",
17        "michelf/php-markdown": "1.9.1",
18        "ramsey/uuid": "3.9.6",
19        "laravel/laravel": "5.5.28"
20    },
21    "require-dev": {
22        "composer/composer": "^2.2"
23    }
24}

日本語訳

問題1
     -ルートcomposer.jsonにはkylekatarnls/laravel-carbon-20.1.0が必要です->kylekatarnls/laravel-carbon-2[0.1.0]で満足できます。
     --kylekatarnls /laravel-carbon-20.1.0では1.25.0としてnesbot/carbon2.0.0-beta.2が必要です->nesbot/ carbon [2.0.0-beta.2]が見つかりましたが、最小安定性と一致しません 。

オプション--with-all-dependencies（-W）を使用して、現在特定のバージョンにロックされているパッケージのアップグレード、ダウングレード、および削除を許可します。

shigurechan@shigurechan-System-Product-Name:~/prg/html/vendor/bin$ composer -W  update
No composer.json in current directory, do you want to use the one at /home/shigurechan/prg/html? [Y,n]? Y
Always want to use the parent dir? Use "composer config --global use-parent-dir true" to change the default.
Composer is operating significantly slower than normal because you do not have the PHP curl extension enabled.
Loading composer repositories with package information
Updating dependencies
Your requirements could not be resolved to an installable set of packages.

  Problem 1
    - Root composer.json requires kylekatarnls/laravel-carbon-2 0.1.0 -> satisfiable by kylekatarnls/laravel-carbon-2[0.1.0].
    - kylekatarnls/laravel-carbon-2 0.1.0 requires nesbot/carbon 2.0.0-beta.2 as 1.25.0 -> found nesbot/carbon[2.0.0-beta.2] but it does not match your minimum-stability.

Use the option --with-all-dependencies (-W) to allow upgrades, downgrades and removals for packages currently locked to specific versions.
shigurechan@shigurechan-System-Product-Name:~/prg/html/vendor/bin$

"nesbot/carbon": "2.0.0-beta.2"

shigurechan@shigurechan-System-Product-Name:~/prg/html/vendor/bin$ composer update
No composer.json in current directory, do you want to use the one at /home/shigurechan/prg/html? [Y,n]? Y
Always want to use the parent dir? Use "composer config --global use-parent-dir true" to change the default.
Composer is operating significantly slower than normal because you do not have the PHP curl extension enabled.
Loading composer repositories with package information
Updating dependencies
Your requirements could not be resolved to an installable set of packages.

  Problem 1
    - laravel/framework[v5.5.0, ..., v5.5.38] require nesbot/carbon ~1.20 -> found nesbot/carbon[1.20.0, ..., 1.39.1] but it conflicts with your root composer.json require (2.0.0-beta.2).
    - laravel/framework[v5.5.39, ..., v5.5.44] require nesbot/carbon ^1.24.1 -> found nesbot/carbon[1.24.1, ..., 1.39.1] but it conflicts with your root composer.json require (2.0.0-beta.2).
    - laravel/framework[v5.5.45, ..., v5.5.50] require nesbot/carbon ^1.26.0 -> found nesbot/carbon[1.26.0, ..., 1.39.1] but it conflicts with your root composer.json require (2.0.0-beta.2).
    - laravel/laravel v5.5.28 requires laravel/framework 5.5.* -> satisfiable by laravel/framework[v5.5.0, ..., v5.5.50].
    - Root composer.json requires laravel/laravel 5.5.28 -> satisfiable by laravel/laravel[v5.5.28].

Use the option --with-all-dependencies (-W) to allow upgrades, downgrades and removals for packages currently locked to specific versions.