Upgrade Node and dependent packages to the latest version

[yhatt]

This PR will upgrade Node LTS and dependent packages to the latest version via yarn upgrade --latest.

Notable changes

Node

• Node LTS version has been bumped to v12.13.1. But we would re-bump as soon as released next security release after Dec 17.
• yarn has been bumped to v1.21.1. A vulnerability reported from npm CLI would affect to yarn < v1.21.1 too.

Dependent packages

• Resolve vulnerability in deep deps: rollup-plugin-terser > serialize-javascript (CVE-2019-16769)
• Migration of rollup official plugins into monorepo is still in progress.
  • rollup-plugin-node-resolve => @rollup/plugin-node-resolve
  • rollup-plugin-url => @rollup/plugin-url
• rollup-plugin-url v3 has been dropped Node 8 support so Marp CLI could not bump it (by failing CI test for against Node 8). But the migrated plugin @rollup/plugin-url v4 is getting back the support of Node 8.
  • However, Node 8 would reach EOL in the end of this year. In next month, Marp CLI also will drop Node 8 support.
• Modify deprecated Puppeteer method page.emulateMedia in favor of page. emulateMediaType.