(#195) Update .nvmrc file with correct Node Version

Closes #195

* Updated `.nvmrc` and `README.md` files with correct Node version
* Added `engines` property to `package.json` to specify Node and npm version ranges
* Added `.npmrc` file and set `engine-strict` property to `true`
* Updated Node version for GitHub actions

.github/workflows/push-actions.yml

@@ -15,7 +15,7 @@ jobs:
             - name: Use Node.js
               uses: actions/setup-node@v4
               with:
-                  node-version: "20.11.0"
+                  node-version: "20.15.0"
                   cache: "npm"
             - name: Install X11 dependencies for robotjs (needed for unit testing on input-mask tests)
               run: sudo apt-get install libxtst-dev libpng++-dev xvfb
@@ -35,7 +35,7 @@ jobs:
             - name: Use Node.js
               uses: actions/setup-node@v4
               with:
-                  node-version: "20.11.0"
+                  node-version: "20.15.0"
                   cache: "npm"
             - name: Set up JDK 11 for x64
               uses: actions/setup-java@v4

.npmrc

@@ -0,0 +1 @@
+engine-strict=true

.nvmrc

@@ -1 +1 @@
-v20.4.0
+v20.15.0

README.md

@@ -10,7 +10,7 @@ A place to learn and share with developers what makes web work accessible. This
 
 - nvm: A Node version manager. It allows you to install several versions of node on the same machine and change versions easily.
   - [Here are instructions in how to install nvm](https://github.com/nvm-sh/nvm#usage)
-  - After installing nvm, install a Node version >= 18 using nvm, ideally `nvm install 20.11.0`
+  - After installing nvm, install a Node version >= 20.15.0 using nvm, ideally `nvm install 20.15.0`
 - npm: a Node Package Manager, usually installed alongside Node
   - More info: [Downloading and installing Node.js and NPM](https://docs.npmjs.com/downloading-and-installing-node-js-and-npm)
 - Lynx: A text-only browser used for testing for how a website will work without graphics turned on.

package.json

@@ -142,6 +142,10 @@
     "text-zoom-event": "^1.7.0",
     "wicg-inert": "^3.1.2"
   },
+  "engines": {
+    "npm": ">=10.7.0 <=10.8.1",
+    "node": ">=20.15.0 <=20.16.0"
+  },
   "bin": {
     "enable-a11y": "bin/server.js"
   },