Redwood Dockerfile uses node 16 as base but current Redwood requires Node 20

[Roadmaster]

Describe the bug This was flagged by a support customer.

"Redwood required node =20.x but the base image generated by fly launch is using 16.3. Just FYI"

• Operating system (unknown)
• fly version (unknown)

** Paste your fly.toml (unknown)

I checked and https://github.com/superfly/flyctl/blob/master/scanner/templates/redwood/Dockerfile hard-codes ARG BASE_IMAGE=node:16.13.0-alpine - this is tunable with --build-args BASE_IMAGE=whatever but I wonder if:

• Is there a way to detect the version of node based on the version of redwood?
• Does it make sense to update the default Dockerfile for new projects to use the node base that the current version of redwood requires?