test: add polyfills to run all tests against node.js 16

[pi0]

🔗 Linked issue

❓ Type of change

• 📖 Documentation (updates to the documentation, readme, or JSdoc annotations)
• 🐞 Bug fix (a non-breaking change that fixes an issue)
• 👌 Enhancement (improving an existing functionality like performance)
• ✨ New feature (a non-breaking change that adds functionality)
• 🧹 Chore (updates to the build process or auxiliary tools and libraries)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

Node.js 16 is still in LTS-supported mode till Sep this year and we might need to support it for a little bit longer. While it hurts, we need to make sure it is supported until then (via polyfills at least)

📝 Checklist

• I have linked an issue or discussion.
• I have updated the documentation accordingly.