Update NodeJS version to match prod

[alxndrsn]

Closes getodk/central#1806

What has been done to verify that this works as intended?

• CI

Why is this the best possible solution? Were any other approaches considered?

Alternative was to include the changes to package-lock.json: running npm i locally removes "peer": true from many dependencies. However, without that change npm ci still seems happy.

How does this change affect users? Describe intentional changes to behavior and behavior that could have accidentally been affected by code changes. In other words, what are the regression risks?

No effect.

Does this change require updates to the API documentation? If so, please update docs/api.yaml as part of this PR.

No.

Before submitting this PR, please make sure you have:

• run make test and confirmed all checks still pass, or witnessed Github completing all checks with success
• verified that any code from external sources are properly credited in comments or that everything is internally sourced

[matthew-white]

We should probably make a similar change to central-frontend as well. Probably after getodk/central-frontend#1549 gets merged, since that also touches package.json.

[matthew-white]

Alternative was to include the changes to package-lock.json: running npm i locally removes "peer": true from many dependencies.

We'll probably need to commit those changes at some point, but I agree that that can happen in a later PR. Perhaps whenever we update dependencies next.