ci: update Swift Format workflow to use Swift 6.1

Change container from swift:6.0 to swift:6.1 to match minimum Swift version requirement in Package.swift

Author: coenttb

.github/workflows/swift-format.yml

@@ -13,7 +13,7 @@ jobs:
   swift_format:
     name: swift-format
     runs-on: ubuntu-latest
-    container: swift:6.0
+    container: swift:6.1
     permissions:
       contents: write
     steps: