Use Swift 6.1

Author: dongjoon-hyun

.github/workflows/build_and_test.yml

@@ -128,8 +128,8 @@ jobs:
     - uses: actions/checkout@v5
     - name: Build
       run: |
-        docker run swiftlang/swift:nightly-6.2-amazonlinux2 uname -a
-        docker run --add-host=host.docker.internal:host-gateway -v $PWD:/spark -w /spark -e SPARK_REMOTE='sc://host.docker.internal:15003' swiftlang/swift:nightly-6.2-amazonlinux2 swift test --no-parallel -c release
+        docker run swift:6.1 uname -a
+        docker run --add-host=host.docker.internal:host-gateway -v $PWD:/spark -w /spark -e SPARK_REMOTE='sc://host.docker.internal:15003' swift:6.1 swift test --no-parallel -c release
 
   integration-test-mac-spark41:
     runs-on: macos-15