[releng] Switch to Node 16.6.2 and npm 7.20.3

Starting with this commit, we will use npm 7+ which will change the format
of the package-lock.json. Everybody in the team will have to upgrade to a
new version of node and npm as a result.

Signed-off-by: Stéphane Bégaudeau <stephane.begaudeau@obeo.fr>

.github/workflows/build.yml

@@ -22,7 +22,7 @@ jobs:
       - name: Setup Node SDK
         uses: actions/setup-node@v1.4.4
         with:
-          node-version: 14
+          node-version: 16
           registry-url: https://npm.pkg.github.com/
 
       - name: Cache Node.js modules

README.adoc

@@ -21,7 +21,7 @@ To build the components in this repository on your own, you will need the follow
 ** Java 11 (Java 12 or later are currently not supported)
 ** https://maven.apache.org[Apache Maven 3.6.3]
 * To build the frontend components:
-** Recent versions of https://nodejs.org/[Node and NPM]: in particular, Node >= 14 is required.
+** Recent versions of https://nodejs.org/[Node and NPM]: in particular, Node >= 16.6 is required along with npm >= 7.20.
 ** https://rollupjs.org/[rollup] (`npm install -g rollup`)
 ** https://github.com/whitecolor/yalc[yalc] (`npm install -g yalc`)