CommonJS to target ES2019

[compulim]

Changelog

Please copy and paste new entries from CHANGELOG.md here.

Changed

• Changed ECMAScript target version, by @compulim, in PR #108
  • CommonJS will target ES2019, changed from ESNext, will support Webpack 4
  • ES Modules will continue to target ESNext

Specific changes

Please list each individual specific change in this pull request.

• Modified packages/react-chain-of-responsibility/tsup.config.ts to target CJS with ES2019
  • Webpack 4 does not understand optional chaining (?.) which introduced in ES2020
  • We can lower the target to older version as we see fit, CJS is not our core scenario and people should understand CJS means they are using older systems