docs: Update installation instructions in CONTRIBUTING.md

[itTkm]

Description

The instructions for installing dependencies for local development were incomplete, so I have updated the setup process to align with the steps outlined in the README.md.

Type of Change

• [ ] 🐛 Bug fix (non-breaking change which fixes an issue)
• [ ] ✨ New feature (non-breaking change which adds functionality)
• [ ] 💥 Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [x] 📚 Documentation update

Pre-flight Checklist

• [x] Changes are limited to a single feature, bugfix or chore (split larger changes into separate PRs)
• [x] Tests are passing (npm test) and code is formatted and linted (npm run format && npm run lint)
• [x] I have reviewed contributor guidelines

Screenshots

Additional Notes