Install nodejs : https://nodejs.org/en/
Install replace-in-file :
npm i -g replace-in-file
Configurer files to scan in files variable :
const files = ['./projects/**/*.html', './projects/**/*.ts', './projects/**/*.scss'];
Add npm script in your project package.json
"migrate:primeflex3": "node scripts/primeflex3-migrate.js"
and start the script :-)