docs: update installation requirements in contributing.md

CONTRIBUTING.md

@@ -207,6 +207,7 @@ You must have the following installed on your system to contribute locally:
 - [`Node.js`](https://nodejs.org/en/) (See the root [.node-version](.node-version) file for the required version. You can find a list of tools on [node-version-usage](https://github.com/shadowspawn/node-version-usage) to switch the version of [`Node.js`](https://nodejs.org/en/) based on [.node-version](.node-version).)
 - [`yarn`](https://yarnpkg.com/en/docs/install)
 - [`python`](https://www.python.org/downloads/) (since we use `node-gyp`. See their [repo](https://github.com/nodejs/node-gyp) for Python version requirements.)
+- [`cmake`](https://cmake.org/) (`sudo apt install cmake` on Unix)
 
 ### Getting Started