Drop support for Swift 5.0

Author: tsolomko

Package.swift

@@ -1,4 +1,4 @@
-// swift-tools-version:5.0
+// swift-tools-version:5.1
 import PackageDescription
 
 let package = Package(

README.md

@@ -1,6 +1,6 @@
 # SWCompression
 
-[![Swift 5.X](https://img.shields.io/badge/Swift-5.X-blue.svg)](https://developer.apple.com/swift/)
+[![Swift 5.1+](https://img.shields.io/badge/Swift-5.1+-blue.svg)](https://developer.apple.com/swift/)
 [![GitHub license](https://img.shields.io/badge/license-MIT-lightgrey.svg)](https://raw.githubusercontent.com/tsolomko/SWCompression/master/LICENSE)
 [![Build Status](https://dev.azure.com/tsolomko/SWCompression/_apis/build/status/tsolomko.SWCompression?branchName=develop)](https://dev.azure.com/tsolomko/SWCompression/_build/latest?definitionId=3&branchName=develop)