Use Swift 6.1

Author: dongjoon-hyun

.github/workflows/build_and_test.yml

@@ -49,7 +49,7 @@ jobs:
           - macos-15
     steps:
     - uses: actions/checkout@v4
-    - uses: swift-actions/setup-swift@v2.2.0
+    - uses: swift-actions/setup-swift@v2.3.0
       with:
         swift-version: "6.1"
     - name: Build