Use import() for espree

[sosukesuzuki]

Description

Checklist

• I’ve added tests to confirm my change works.
• (If changing the API or CLI) I’ve documented the changes I’ve made (in the docs/ directory).
• (If the change is user-facing) I’ve added my changes to changelog_unreleased/*/XXXX.md file following changelog_unreleased/TEMPLATE.md.
• I’ve read the contributing guidelines.

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[fisker]

Size Change: +224 kB (+1%)

Total Size: 15.3 MB

Filename	Size	Change
./dist/esm/parser-espree.mjs	251 kB	+112 kB (+81%)	🆘
./dist/parser-espree.js	251 kB	+112 kB (+81%)	🆘

[sosukesuzuki]

I've just knew why bundle size is increased. parser-espree depends on espree(ESM). espree(ESM) depends on acorn (ESM). But, parser-acorn depends on acorn (CJS). So both acorn(ESM) and acorn( CJS) are bundled to dist/parser-espree.js.

It would be best to wait for ESM support in acorn-jsx before resuming this work.