Package suggestion: unfetch for `Promise polyfills`

[b1ek]

unfetch is an alternative to fetch-polyfill

It is only 950 bytes in size, 500 bytes gzipped, and does pretty much the same as any other fetch polyfill

• [x] Package has sufficient overlap in functionality to act as a replacement.
• [x] Package is actively maintained, and/or stable for use.
• [x] Package has at least 1000 weekly downloads on NPM or is relatively popular on GitHub.
• [x] This package is a better alternative to what is already suggested for this category (please explain why), or the category is new.