Upgrade dependent packages to the latest version

[yhatt]

Notable changes

Replaced packages

• npm-run-all has been replaced into npm-run-all2.
  • marp-vscode has been already replaced it: https://github.com/marp-team/marp-vscode/blob/main/package.json#L310
• eslint-plugin-import has been replaced into eslint-plugin-import-x, for updating ESLint v9.

Major updates

• markdown-it v14
  • markdown-it has been rewritten in ESM. We also may have to need to replace the codebase of Marpit into ESM in near future.
  • It now follows the latest CommonMark spec v0.31.2.
  • Resolves?: marp-team/marp-cli#574.
• ESLint v9
  • It requires to replace the configuration into the flat config. This PR is using ESLINT_USE_FLAT_CONFIG=false, but I'll work on migration in another PR.
  • https://eslint.org/docs/latest/use/migrate-to-9.0.0