Add support for Bun

[kytta]

This PR adds support for Bun:

• info is still queried from NPM, as Bun does not have an info command
• update is done via bun update
• tests use bun pm ls --all to query the lockfile

Closes #25

[ai]

I will combine both your PRs and both of you will be mentioned in Cult of Martians.

[ai]

Do you have Twitter account to mention you in release tweet?

[ai]

Do you have Twitter account to mention you in release tweet?

[kytta]

Do you have Twitter account to mention you in release tweet?

Yes, it's https://twitter.com/kyttawashere (albeit inactive)