[feat] add koa as peerDependencies

[imballinst]

Describe the feature

Currently, koa is listed as devDependencies here (as it should).

bodyparser/package.json

Line 59 in 664cd7c

"koa": "^2.14.1",

However, given that koa is also needed when using this package, I somewhat feel like it's a good idea to put it in peerDependencies, just in case? I stumbled upon this error where koa dependency inside this part can't be found:

bodyparser/src/body-parser.ts

Line 2 in 664cd7c

import type * as Koa from 'koa';

I am using Yarn 3.6.4 with nodeLinker: pnpm with rather strict setup, so a package needs to be specified explicitly otherwise it can't be "linked". So in this case, since koa is neither added as dependencies or peerDependencies, Yarn can't resolve it, hence making the declare module "koa" not affecting the actual application.

I propose to add this:

"peerDependencies": {
  "koa": "^2.14.1"
}

into package.json, so that stricter package managers can pick the module up from inside node_modules. Let me know what you think. Thanks!

Checklist

• I have searched through GitHub issues for similar issues.
• I have completely read through the README and documentation.