See https://gitlab.com/groups/gitlab-org/-/epics/9477. node@18 is the
latest LTS and the new version has some nice features we might end up
using (e.g. more parity on the Intl API with browsers).

In order to ensure that node version bump result in re-compiling of
assets, we also tell the asset hashing that any change in .nvmrc
requires a full recompilation.

Changelog: changed