fix: feeType=positive_slippage logic [TKR-81]

[romainbutteaud]

Description

• API change: https://github.com/0xProject/protocol/pull/209

Testing Instructions

Checklist

• [ ] Update documentation as needed. Website Documentation PR:

• [ ] Prefix PR title with [WIP] if necessary.

• [ ] Add tests to cover changes as needed.

• [ ] Test changes on the staging environment with Matcha API Staging.

  • [ ] SRA/Limit orders
  • [ ] Swap endpoints
  • [ ] Meta transaction endpoints
  • [ ] Depth charts

  For more information see 0x API Matcha smoke test runbook in Quip.

[kimpers]

We doing anything with this @romainbutteaud, @dekz? 😄