fix(types): removing unnecessary types for the generic list utility

Fixing some ts-ignores in the slide-layout.tsx by removing unnecessary typings.

[x] Bug fix (non-breaking change which fixes an issue)
[ ] New feature (non-breaking change which adds functionality)
[ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
[ ] This change requires a documentation update

Running the CI checks locally, not a functional change.

[ ] I have included a changeset if this change will require a version change to one of the packages.
[x] I have performed a self-review of my own code
[ ] I have commented my code, particularly in hard-to-understand areas
[ ] I have made corresponding changes to the documentation
[x] I have run pnpm run check:ci and all checks pass
[ ] I have added tests that prove my fix is effective or that my feature works
[ ] My changes generate no new warnings
[ ] Any dependent changes have been merged and published in downstream modules

FormidableLabs / spectacle