ここにあるとおりにやったのだけれど、うまくいかなかった。

• https://www.drupal.org/docs/updating-drupal/updating-drupal-core-via-composer
• https://minokamo.tokyo/2021/05/24/3710/

$ composer outdated "drupal/*"
Color legend:
- patch or minor release available - update recommended
- major release available - update possible
drupal/core                   9.3.2  9.3.3 Drupal is an open source content management platform powering millions of websites and applications.
drupal/core-composer-scaffold 9.3.2  9.3.3 A flexible Composer project scaffold builder.
drupal/core-dev               9.3.2  9.3.3 require-dev dependencies from drupal/drupal; use in addition to drupal/core-recommended to run tes...
drupal/core-project-message   9.3.2  9.3.3 Adds a message after Composer installation.
drupal/core-recommended       9.3.2  9.3.3 Locked core dependencies; require this project INSTEAD OF drupal/core.
drupal/core-vendor-hardening  8.9.20 9.3.3 Hardens the vendor directory for when it's in the docroot.

説明通りにUpdateする

$ composer update drupal/core "drupal/core-*" --with-all-dependencies
Loading composer repositories with package information
Updating dependencies
Your requirements could not be resolved to an installable set of packages.
 
  Problem 1
    - composer/installers[v1.7.0, ..., v1.8.0] require composer-plugin-api ^1.0 -> found composer-plugin-api[2.2.0] but it does not match the constraint.
    - Root composer.json requires composer/installers ^1.2 -> satisfiable by composer/installers[v1.7.0, v1.8.0].

問題あるらしい。composerのapiが古いとか言っているように思える、この文章をググると下記のページみたいなのが出る。

https://drupal.stackexchange.com/questions/297806/trouble-after-updating-to-2-0

何をすべきかはっきりわからない

何をすべきかはっきりわからないが、何かが古いのだろう。vendorを消して　composer　updateすると書いてあるが、何もせずにやってみた。

$ composer update
Loading composer repositories with package information
Updating dependencies
Lock file operations: 0 installs, 9 updates, 2 removals
  - Removing nette/finder (v2.5.3)
  - Removing nette/utils (v3.2.6)
  - Upgrading composer/composer (2.2.3 => 2.2.5)
  - Upgrading composer/pcre (1.0.0 => 1.0.1)
  - Upgrading drupal/core (9.3.2 => 9.3.3)
  - Upgrading drupal/core-composer-scaffold (9.3.2 => 9.3.3)
  - Upgrading drupal/core-dev (9.3.2 => 9.3.3)
  - Upgrading drupal/core-project-message (9.3.2 => 9.3.3)
  - Upgrading drupal/core-recommended (9.3.2 => 9.3.3)
  - Upgrading mglaman/phpstan-drupal (1.1.5 => 1.1.9)
  - Upgrading phpstan/phpstan (1.3.1 => 1.4.2)
Writing lock file
Installing dependencies from lock file (including require-dev)
Package operations: 0 installs, 9 updates, 2 removals
  - Downloading composer/pcre (1.0.1)
  - Downloading drupal/core (9.3.3)
  - Downloading composer/composer (2.2.5)
  - Downloading phpstan/phpstan (1.4.2)
  - Downloading mglaman/phpstan-drupal (1.1.9)
  - Removing nette/utils (v3.2.6)
  - Removing nette/finder (v2.5.3)
  - Upgrading drupal/core-composer-scaffold (9.3.2 => 9.3.3): Extracting archive
  - Upgrading drupal/core-project-message (9.3.2 => 9.3.3): Extracting archive
  - Upgrading composer/pcre (1.0.0 => 1.0.1): Extracting archive
  - Upgrading drupal/core (9.3.2 => 9.3.3): Extracting archive
  - Upgrading composer/composer (2.2.3 => 2.2.5): Extracting archive
  - Upgrading drupal/core-dev (9.3.2 => 9.3.3)
  - Upgrading drupal/core-recommended (9.3.2 => 9.3.3)
  - Upgrading phpstan/phpstan (1.3.1 => 1.4.2): Extracting archive
  - Upgrading mglaman/phpstan-drupal (1.1.5 => 1.1.9): Extracting archive
    Cleaning: composer/composer
Package container-interop/container-interop is abandoned, you should avoid using it. Use psr/container instead.
Package doctrine/reflection is abandoned, you should avoid using it. Use roave/better-reflection instead.
Generating autoload files
Hardening vendor directory with .htaccess and web.config files.
84 packages you are using are looking for funding.
Use the `composer fund` command to find out more!
Cleaning vendor directory.

あれれれ、なんかおわってるっぽい。9.3.2　⇒　9.3.3 と記載が出てる。

わからないけど、とりあえず、update.phpを実行

できてるように見える。