[CDF-25130] CDF-25130 Function schedule validation (#1691)

# Description

The `FunctionScheduleYAML.data` field is currently incorrectly expecting
input data for functions to be a `dict[str, str]` causing the
following incorrect warning.

![image](https://github.com/user-attachments/assets/c0120d4e-8ba7-462b-9229-150055dfc51a)

## Changelog

- [x] Patch
- [ ] Minor
- [ ] Skip

## cdf

### Fixed

- When running `cdf build` on a Function Schedule with nested input
data, the user no longer gets a `ResourceFormatWarning`.

## templates

No changes.
