Update `create-turbo` to use carat versions. (#8448)
### Description
Previously, we were putting `turbo@latest` into `package.json` for the
`devDep` when creating a repo with `create-turbo`. Generally, using the
`latest` tag isn't a great practice, so let's use the carat version of
`create-turbo` itself instead. We're safe to use this since
`create-turbo`'s version tracks along with `turbo` itself.
### Testing Instructions
Tested locally by building the package and running the `dist/cli.js`. I
also tried it out with canary and stable versions manually placed into
the `create-turbo` `package.json#version`.
