chore: drop support for node < 20

[Fdawgs]

This PR:

• Drops support for Node < 20 (breaking change)
• Bumps dev dependencies to their latest versions, resolving vulnerabilities raised by npm audit
• Removes the unused @rollup/plugin-terser plugin
• Replaces the deprecated trailingComma biome config value with trailingCommas

[Fdawgs]

Test failure due to Node 16 no longer being supported by a dep.
Probably time to drop it as it was EOL in April 2022, drop Node 18 which is EOL next month, and update the engines in package.json?

[kibertoad]

@Fdawgs sounds good! can you do the changes? we can release as semver major

[Fdawgs]

@Fdawgs sounds good! can you do the changes? we can release as semver major

Done!

[kibertoad]

Thank you!