Mention required NodeJS 14.x in CONTRIBUTING.md

[dgolovin]

When using NodeJS version higher than 14 npm install fails to install @nut-tree/opencv-build-linux package

Signed-off-by: Denis Golovin dgolovin@redhat.com

[angelozerr]

It seems that I have similar problem with

• Windows OS
• NodeJS v10.16.0
• npm 7.19.0

npm ERR! path C:\Users\azerr\git\vscode-quarkus\node_modules\opencv4nodejs-prebuilt
npm ERR! command failed
npm ERR! command C:\WINDOWS\system32\cmd.exe /d /s /c prebuild-install || (node ./install/dependencies.js && node ./install/install.js)
npm ERR! Installing prebuilt OpenCV vundefined for plattform win32
npm ERR! (node:19068) ExperimentalWarning: The fs.promises API is experimental
npm ERR! npm WARN old lockfile 
npm ERR! npm WARN old lockfile The package-lock.json file was created with an old version of npm,
npm ERR! npm WARN old lockfile so supplemental metadata must be fetched from the registry.
npm ERR! npm WARN old lockfile 
npm ERR! npm WARN old lockfile This is a one-time fix-up, please be patient...
npm ERR! npm WARN old lockfile 
npm ERR! npm ERR! code ETARGET
npm ERR! npm ERR! notarget No matching version found for @nut-tree/opencv-build-win32@undefined.
npm ERR! npm ERR! notarget In most cases you or one of your dependencies are requesting
npm ERR! npm ERR! notarget a package version that doesn't exist.
npm ERR! 
npm ERR! npm ERR! A complete log of this run can be found in:
npm ERR! npm ERR!     C:\Users\azerr\AppData\Local\npm-cache\_logs\2021-08-04T12_30_47_838Z-debug.log
npm ERR! child_process.js:669
npm ERR!     throw err;
npm ERR!     ^
npm ERR! 
npm ERR! Error: Command failed: npm install @nut-tree/opencv-build-win32@undefined
npm ERR! (node:19068) ExperimentalWarning: The fs.promises API is experimental
npm ERR! npm WARN old lockfile 
npm ERR! npm WARN old lockfile The package-lock.json file was created with an old version of npm,
npm ERR! npm WARN old lockfile so supplemental metadata must be fetched from the registry.

[dgolovin]

@angelozerr I suggest to remove package-lock.json before running 'npm install'. Node.js 10.16.0 works for me.
@datho7561 I put version range int doc.

[angelozerr]

@dgolovin my problem was about npm version (not about node version). Indeed I install as global the npm version 6.14.14 and it works great again.

[datho7561]

I think this change looks good in terms of listing the NodeJS requirement. I think we can merge this. We can add another change to list the NPM requirement (6.y.z)