fix: warn ./.cache/slice/server-slice.js

[schettn]

ref: https://github.com/gatsbyjs/gatsby/issues/38483#issuecomment-1870299093

Currently there is a issue where gatsby develop will fail sometimes with the following warning:

warn ./.cache/slice/server-slice.js
Attempted import error: 'createContentDigest' is not exported from 'gatsby-core-utils/create-content-digest' (imported as
'createContentDigest').

This leads to a total crash on the client side, thus only a white screen appears.

My proposed change will fix that.

[schettn]

Hi @pieh!

Please take a look. I really need this in order to work with Gatsby.