Update Node.js version requirement and package manager requirement

[clicktodev]

Description

Specify that the project requires Node.js version 20 or higher in the package.json file.
This is to discourage the usage of unsupported node releases during development.

[github-actions]

📦 Bundle size

Full ESM build, minified and gzipped.

	Before	After	Diff
WebGL	356.38 86.5	356.38 86.5	+0 B +0 B
WebGPU	609.66 171.01	609.66 171.01	+0 B +0 B
WebGPU Nodes	608.27 170.75	608.27 170.75	+0 B +0 B

🌳 Bundle size after tree-shaking

Minimal build including a renderer, camera, empty scene, and dependencies.

	Before	After	Diff
WebGL	488 121.24	488 121.24	+0 B +0 B
WebGPU	678.52 186.29	678.52 186.29	+0 B +0 B
WebGPU Nodes	620.51 169.56	620.51 169.56	+0 B +0 B

[Mugen87]

What problems occur if you try to build the project with node 19 or a lower version?

[clicktodev]

nothing should break but this is mainly to encourage the usage of actively maintained releases to reduce the chances of node bugs present in unmaintained releases from affecting the dev env or build process.

[Mugen87]

What I don't like about such entries is that we hardly encode a version in package.json that we now have to maintain over the years. I. know this is a minor task but the smaller package.json is, the less we have to think about.

@mrdoob I personally favor simplicity but if you think that change is worth it I won't object merging it.

[clicktodev]

also added an package manager check to avoid someone accidentally committing a yarn or pnpm lock file

[clicktodev]

actually considering the package.json is also published in npm, this may affect consumers of the lib, not just the repo devs.
maybe the devEngines property is more suitable