chore: release 19.0.0

[github-actions]

🤖 I have created a release *beep* *boop*

19.0.0 (2020-08-04)

⚠ BREAKING CHANGES

• adds support for ESM and Deno (feat!: adds support for ESM and Deno yargs/yargs-parser#295)
• ts: projects using @types/yargs-parser may see variations in type definitions.
• drops Node 6. begin following Node.js LTS schedule (build!: drops Node 6. begin following Node.js LTS schedule yargs/yargs-parser#278)

Features

• adds support for ESM and Deno (#295) (195bc4a)
• deps: update to latest camelcase/decamelize (#281) (8931ab0)

Bug Fixes

• deps: update dependency decamelize to v3 (#274) (4d98698)
• types: switch back to using Partial types (#293) (bdc80ba)

Build System

• drops Node 6. begin following Node.js LTS schedule (#278) (9014ed7)

Code Refactoring

• ts: move index.js to TypeScript (#292) (f78d2b9)

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