Explicitly set to latest Swift version available on GitHub CI

Author: Jeehut

.github/workflows/main.yml

@@ -14,6 +14,9 @@ jobs:
     steps:
       - uses: actions/checkout@v4
 
+      - name: Use latest Swift version
+        uses: swift-actions/setup-swift@v2
+
       - name: Run tests
         run: swift test
 
@@ -23,5 +26,8 @@ jobs:
     steps:
       - uses: actions/checkout@v4
 
+      - name: Use latest Swift version
+        uses: swift-actions/setup-swift@v2
+
       - name: Run tests
         run: swift test