Isomorphic Fetch API

Isomorphic Unfetch is a lightweight JavaScript library that provides a universal `fetch` API implementation, automatically switching between `unfetch` (a minimal `fetch` ponyfill for browsers) and `node-fetch` (a `fetch` implementation for Node.js) based on the execution environment. The current stable version is 5.0.0. This package aims for a small footprint and consistent behavior across client-side and server-side JavaScript, abstracting away environment-specific `fetch` implementations. It provides both a ponyfill (default named import) and a global polyfill (side-effect import). Recent major updates include the adoption of `node-fetch` v3.x, which mandates Node.js >= 12.20.0, and the addition of first-class TypeScript definitions and Package Exports for improved module resolution. It focuses on simplicity and compatibility with standard `fetch` API usage.