... has reached a new major version, and so it makes sense to carefully evaluate what has changed and make careful adjustments to the code that relies on it to work with the new release.
In particular, "Breaking changes from v2 -> v3" mentions that queries are now asynchronous.
The library that facilitates access to the postgres database from the backend functions written in nodejs ...
https://github.com/littermap/littermap-aws-backend/blob/1b16f497497bf44da07823314ee00da6207942a6/layers/postgres/nodejs/package.json#L5
... has reached a new major version, and so it makes sense to carefully evaluate what has changed and make careful adjustments to the code that relies on it to work with the new release.
In particular, "Breaking changes from v2 -> v3" mentions that queries are now asynchronous.