Use swift 5.9

Author: adborbas

.github/workflows/ci.yml

@@ -21,7 +21,7 @@ jobs:
       - name: Set up Swift on Ubuntu
         uses: fwal/setup-swift@v1
         with:
-          swift-version: '5.7.1'
+          swift-version: '5.9'
       - name: Build on Ubuntu
         run: swift build
       - name: Test on Ubuntu

Package.swift

@@ -1,4 +1,4 @@
-// swift-tools-version:5.7.1
+// swift-tools-version:5.9
 import PackageDescription
 
 let package = Package(