fix: change RemoveIndexSignature to OmitIndexSignature

# The issue The `type-fest` package, no longer has a `RemoveIndexSignature` type. # The solution I renamed the `RemoveIndexSignature` import to `OmitIndexSignature`. # Additional This also solves a bug when using the values of a scoped slots in the `renderMethod`. ```js render(MyComponent, { slots: { mySlot: (props) => 'Hello, world' // The `props` parameter had the type of any, this is now fixed and has the correct type } }); ```