Infra: remove unneeded swiftLanguageVersions param (#444) [skip ci]

Co-authored-by: Jeongsang Kim <jeongsang.kim@nol-universe.com>
Co-authored-by: David Roman <2538074+davdroman@users.noreply.github.com>

Author: 3 people

Package@swift-6.0.swift

@@ -19,6 +19,5 @@ let package = Package(
             name: "SwiftUIIntrospect",
             path: "Sources"
         ),
-    ],
-    swiftLanguageVersions: [.v6]
+    ]
 )