tslib must be a dependency and not a devDependency

[iainmerrick]

(Borrowing from dojo/core#372, which has a really clear writeup of the same bug in a different NPM package)

When this package is installed, the generated .js files contain require("tslib"). So tslib needs to be in dependencies, not just devDependencies.

Here's a simple repro case:

$ npm install remix-mount-routes --no-package-lock --global-style   

added 4 packages, and audited 5 packages in 2s

found 0 vulnerabilities
$ node -e "require('remix-mount-routes')"                           
node:internal/modules/cjs/loader:936
  throw err;
  ^

Error: Cannot find module 'tslib'

This bug is often disguised when using npm, as some other package in your project will likely depend on tslib. But it won't work in pnpm without --shamefully-hoist as pnpm doesn't expose transitive dependencies by default.