SWIFT_VERSION '3.1' is unsupported, supported versions are: 4.0, 4.2, 5.0.

## Expected Behavior
Build succeeded

## Actual Behavior
Build failed with error: 
SWIFT_VERSION '3.1' is unsupported, supported versions are: 4.0, 4.2, 5.0.

## Steps to Reproduce the Problem

  1. Pod install
  1. Build app
  1. error occurs

## Specifications

  - Version:
  - Platform:
  - Subsystem:
