Bump to Swift 5.1

[lucas34]

No description provided.

[lucas-bot]

	3 Warnings
⚠️	The Package.swift has been updated but not the Package.resolved. Did you forgot to run swift package update ?
⚠️	The podspec was updated, but there were no changes in either the Cartfile nor Package.swift. Did you forget updating Cartfile or Package.swift?
⚠️	The Package.swift was updated, but there were no changes in either the podspec nor Cartfile. Did you forget updating podspec or Cartfile?

Generated by 🚫 Danger

[codecov]

Codecov Report

Merging #280 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #280   +/-   ##
=======================================
  Coverage   95.56%   95.56%           
=======================================
  Files          28       28           
  Lines        2163     2163           
=======================================
  Hits         2067     2067           
  Misses         96       96