Set engines field to node 20 and above

[Andarist]

node 18 has its EOL literally in 4 days

[changeset-bot]

🦋 Changeset detected

Latest commit: d6b1167

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 4 packages

Name	Type
@manypkg/get-packages	Major
@manypkg/find-root	Major
@manypkg/tools	Major
@manypkg/cli	Minor

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Click here if you're a maintainer who wants to add another changeset to this PR

[bluwy]

If we set to node 20, will we also do the same for changesets later? I feel like it's a bit early to move to v20 even if it's EOL soon, as consumers might still want to stick or support node 18, but I guess that depends on the timeframe changesets v3 is out and stable.

Also, is it intentional that gatsby-source-workspace doesn't have a changeset?

---

Maybe we should also update this field here:

manypkg/babel.config.js

Lines 4 to 7 in 1763058

	"@babel/preset-env",
	{
	targets: { node: 14 },
	},

[bluwy]

Ok with node 20 support if we want to directly extend to it.