ci: Trying Swift 6.1

Author: NeedleInAJayStack

.github/workflows/test.yaml

@@ -11,6 +11,8 @@ jobs:
     runs-on: macos-latest
     steps:
     - uses: swift-actions/setup-swift@v2
+      with:
+        swift-version: '6.1'
     - uses: actions/checkout@v4
     - name: Build and test
       run: |