Remove Volta from deck.gl (#9970)

* chore(examples): replace deprecated `assert` with `with` for JSON imports

The `assert` keyword for import attributes is deprecated in Node.js 18+
in favor of the `with` keyword. This change fixes deprecation warnings
when running tests and ensures compatibility with modern Node.js versions.

The `with` syntax requires Node.js 18.20.0+, so the .nvmrc is updated to 18.20.8.

Co-Authored-By: Claude Opus 4.5 <[email protected]>

* Initial plan

* Remove Volta from deck.gl

Co-authored-by: chrisgervang <[email protected]>

---------

Co-authored-by: Chris Gervang <[email protected]>
Co-authored-by: Claude Opus 4.5 <[email protected]>
Co-authored-by: Chris Gervang <[email protected]>
Co-authored-by: copilot-swe-agent[bot] <[email protected]>
Co-authored-by: chrisgervang <[email protected]>

Author: 3 people

CONTRIBUTING.md

@@ -10,7 +10,7 @@ PRs and bug reports are welcome, and we are actively looking for new maintainers
 The **master** branch is the active development branch.
 
 Building deck.gl locally from the source requires node.js `>=18`. Further limitations on the Node version may be imposed by [puppeteer](https://github.com/puppeteer/puppeteer#usage) and [headless-gl](https://github.com/stackgl/headless-gl#supported-platforms-and-nodejs-versions).
-We use [yarn](https://yarnpkg.com/en/docs/install) to manage the dependencies of deck.gl. The project's automated builds use Node [corepack](https://github.com/nodejs/corepack) to manage the yarn version. For local development, you can use [volta](https://docs.volta.sh/guide/getting-started), [nvm](https://github.com/nvm-sh/nvm), or any other Node version manager of your choice - configuration files are provided for all major tools (.nvmrc and volta settings in package.json).
+We use [yarn](https://yarnpkg.com/en/docs/install) to manage the dependencies of deck.gl. The project's automated builds use Node [corepack](https://github.com/nodejs/corepack) to manage the yarn version. For local development, you can use [nvm](https://github.com/nvm-sh/nvm) or any other Node version manager of your choice - a `.nvmrc` configuration file is provided.
 
 ```bash
 git checkout master

package.json

@@ -65,9 +65,5 @@
   "engines": {
     "node": ">=14"
   },
-  "volta": {
-    "node": "18.19.0",
-    "yarn": "1.22.19"
-  },
   "packageManager": "[email protected]"
 }

website/package.json

@@ -59,9 +59,5 @@
     ">0.2% and supports async-functions",
     "not dead"
   ],
-  "volta": {
-    "node": "18.19.0",
-    "yarn": "1.22.19"
-  },
   "packageManager": "[email protected]"
 }