Error message when reverting version that doesn't exist could be improved

When trying to revert a version that doesn't exist we get the following error message:

> gleam hex revert --package birdie --version 1.234234.2
error: Hex API failure

There was a problem when using the Hex API.

This was error from the Hex client library:

    Resource was not found

I think a much better error would look something like this:

> gleam hex revert --package birdie --version 1.234234.2

error: Hex API failure

There is no version 1.234234.2 of the package birdie.