chore: bump @netlify/build to 29.21.1

[estephinson]

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Summary

Bump because renovate sad

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[github-actions]

📊 Benchmark results

Comparing with da54676

• Dependency count: 1,365 (no change)
• Package size: 366 MB (no change)

[eduardoboucas]

You can see in #986 that the update was picked up by Renovate, but it was rate-limited. You can click on the checkbox next to the package to force it to create the PR.

If you do decide to do the update manually (which I would avoid if you can help it), I would use a fix: or feat: prefix or release-please won't generate a release. Also, we're currently pinning @netlify/build to a specific version and you're changing it to a range here.

[estephinson]

I am a renovate newbie so I really appreciate that - I was triggering it a billion times via the dashboard but every time coming up that it was skipping. Had a google and found nothing related to that, really appreciate the pointer!