Updates and ESM support

[novemberborn]

Fixes #5.

• Simplify issue template
• Upgrade XO and apply changes
• Update dependencies
• Upgrade to ESM
• Match AVA 4 Node.js versions
• Update CI
• Support ESM files

[novemberborn]

Thwarted by CI failures! Why the heck is this failing in Node.js 12 and 14, but not locally?! https://github.com/avajs/typescript/runs/4072812179?check_suite_focus=true

Sure I can add "lib": ["es2015"] but that breaks linting: https://github.com/avajs/typescript/runs/4072834457?check_suite_focus=true

And why is it complaining about an ESLint type definition anyhow.

[sindresorhus]

Thwarted by CI failures! Why the heck is this failing in Node.js 12 and 14, but not locally?!

Since it's only failing on Node.js 12 and 14, which use npm 6, not 7, I would guess it has something to do with dependency resolution. I had a lot of problems with npm 6 in XO... Try forcing the latest npm version maybe?

[sindresorhus]

Unrelated by both actions/checkout@v1, actions/setup-node@v1, and codecov/codecov-action@v1 can be bumped to v2.

[novemberborn]

Since it's only failing on Node.js 12 and 14, which use npm 6, not 7, I would guess it has something to do with dependency resolution. I had a lot of problems with npm 6 in XO... Try forcing the latest npm version maybe?

Yes, that does the trick! Well spotted.

Unrelated by both actions/checkout@v1, actions/setup-node@v1, and codecov/codecov-action@v1 can be bumped to v2.

Already taken care of in this PR 😄