Upgrade development Node.js and dependent packages

[yhatt]

Node.js 18

Marp Core is using Node.js v18 LTS for development now.

Dependent packages

• rollup and plugins have major update (v3).
  • Updated rollup.config.js to ES module .mjs.
• Jest has a major update v29.
  • Update the format of snapshots.
  • Jest is no longer supported outdated Node.js 12.
    • Marp Core is still installable to Node.js 12 project until next major release, but there is no longer guaranteed to keep working with it.
  • ➡️ We have dropped continuous test against Node.js 12.
    • Marp CLI for development (only supports active Node.js) also can upgrade to v2 by dropping continuous testing against outdated Node.js.