Set Swift 6 as the minimum build tools version (#610)

Author: andrewdmontgomery

Demo/Demo/Base.xcconfig

@@ -7,3 +7,6 @@ CODE_SIGN_IDENTITY = Apple Development: Created via API (886NX39KP6)
 
 // Default the build number to 0 and delegate to build scripts for setting an appropriate number.
 CURRENT_PROJECT_VERSION = 0
+
+SWIFT_VERSION = 5.0
+SWIFT_STRICT_CONCURRENCY = complete

Package.swift

@@ -1,4 +1,4 @@
-// swift-tools-version: 5.10
+// swift-tools-version: 6.0
 // The swift-tools-version declares the minimum version of Swift required to build this package.
 
 import PackageDescription
@@ -33,23 +33,26 @@ let package = Package(
             name: "Gravatar",
             resources: [.process("Resources")],
             swiftSettings: [
-                .enableExperimentalFeature("StrictConcurrency")
+                .swiftLanguageMode(.v5),
+                .enableUpcomingFeature("StrictConcurrency")
             ]
         ),
         .testTarget(
             name: "GravatarTests",
             dependencies: ["Gravatar", "TestHelpers"],
             resources: [.process("Resources")],
             swiftSettings: [
-                .enableExperimentalFeature("StrictConcurrency")
+                .swiftLanguageMode(.v5),
+                .enableUpcomingFeature("StrictConcurrency")
             ]
         ),
         .target(
             name: "GravatarUI",
             dependencies: ["Gravatar"],
             resources: [.process("Resources")],
             swiftSettings: [
-                .enableExperimentalFeature("StrictConcurrency")
+                .swiftLanguageMode(.v5),
+                .enableUpcomingFeature("StrictConcurrency")
             ]
         ),
         .testTarget(
@@ -59,15 +62,17 @@ let package = Package(
             resources: [.process("Resources"),
                         .process("__Snapshots__")],
             swiftSettings: [
-                .enableExperimentalFeature("StrictConcurrency")
+                .swiftLanguageMode(.v5),
+                .enableUpcomingFeature("StrictConcurrency")
             ]
         ),
         .target(
             name: "TestHelpers",
             dependencies: ["Gravatar"],
             resources: [.process("Resources")],
             swiftSettings: [
-                .enableExperimentalFeature("StrictConcurrency")
+                .swiftLanguageMode(.v5),
+                .enableUpcomingFeature("StrictConcurrency")
             ]
         )
     ]