Add types/node-fetch to dependencies rather than devDependencies

Using this library in a typescript project causes the following error on compile:

Could not find a declaration file for module 'node-fetch'. '/app/node_modules/node-fetch/lib/index.js' implicitly has an 'any' type.

This is caused by @types/node-fetch being a devDependency rather than a dependency and thus not being installed when consuming it as an npm package. Installing this @types/node-fetch module manually resolves the issue but is a messy workaround.

The Typescript handbook advises to add dependent @types to dependencies to mitigate this problem. It is also commonly done in other typescript libs that do not bundle their output, see e.g. got.

[isaachinman]

@sonologico Can we get a response here? Especially with Node v18, which has built-in fetch, the node-fetch dependency needs to be fixed.

[sonologico]

@types/node-fetch moved into dependencies in 5.1.2. Thanks for reporting this.