build: Monorepo root dependencies as devDependencies (#2911)

Changed root package.json `dependencies` to `devDependencies`. It
doesn't change any functionality, but allows us to upgrade
`@manypkg/cli` (i.e. unblocks
#2909).

The change suggested by `@manypkg/cli` makes the dependency setup more
consistent. See more detailed explanation here:
https://github.com/Thinkmill/manypkg?tab=readme-ov-file#root-has-prod-dependencies.
- it would be also possible to add `ROOT_HAS_PROD_DEPENDENCIES` to
`manypkg'`s `ignoredRules` if we prefer not to do this change

## Other changes

Also updated `@manypkg/cli` to latest.

Author: teogeb