Rank feature query function typing fixes

[jurgisnosto]

Description

This PR fixes incorrect typings in rank feature saturation, sigmoid and log query functions. More specifically, pivot and scaling_factor fields should accept floats instead of integers. This can be confirmed for each function:

• Saturation - elastic source, official client source
• Sigmoid - elastic source, official client source
• Log - elastic source, official client source

Official docs can be found here.

Context

The error was encounter while migrating from the deprecated high level rest client to elastic4s. We are using saturation function with float values which cannot be changed, so the migration is on hold until the PR is merged. Please let me know if you need any additional input from me

[Philippus]

Nice catch! I think the examples threw me off, as they only show whole numbers.