Upgrade Swift to latest version

## Expected Behavior

Successful framework compilation

## Actual Behavior

Skipped installing SpreadsheetView.framework binary due to the error:
"Incompatible Swift version - framework was built with 3.1 (swiftlang-802.0.53 clang-802.0.42) and the local version is 5.0.1 (swiftlang-1001.0.82.4 clang-1001.0.46.5)."

## Steps to Reproduce the Problem

carthage update --platform iOS

## Specifications

- Xcode version: 10.3
- iOS version: 12.0
- Dependency manager + version: carthage version 0.33.0

Start by running `carthage update --platform iOS` with the listed Xcode 10.3 and iOS 12.0 setup, then inspect how SpreadsheetView.framework is built and distributed. Done means the framework installs successfully and compilation no longer reports an incompatible Swift version.

Written by the indexing model from the issue text.