Swift 6.0 support

Package.swift

@@ -1,4 +1,4 @@
-// swift-tools-version:5.5
+// swift-tools-version:6.0
 // The swift-tools-version declares the minimum version of Swift required to build this package.
 
 import PackageDescription
@@ -10,7 +10,16 @@ let package = Package(
     .library(name: "ValidationKit", targets: ["ValidationKit"]),
   ],
   targets: [
-    .target(name: "ValidationKit", dependencies: [], resources: [.process("Resources")]),
-    .testTarget(name: "ValidationKitTests", dependencies: ["ValidationKit"]),
+    .target(
+      name: "ValidationKit",
+      resources: [.process("Resources")],
+      swiftSettings: [
+        .enableUpcomingFeature("StrictConcurrency")
+      ]
+    ),
+    .testTarget(
+      name: "ValidationKitTests",
+      dependencies: ["ValidationKit"]
+    ),
   ]
 )

Sources/ValidationKit/ValidationError.swift

@@ -9,7 +9,7 @@
 import Foundation
 
 /// An error that occurs when input validation does not pass.
-public struct ValidationError: Error, LocalizedError, Equatable, Hashable {
+public struct ValidationError: Error, LocalizedError, Equatable, Hashable, Sendable {
   public let localizedDescription: String
   public var errorDescription: String? {
     localizedDescription

Sources/ValidationKit/ValidationResult.swift

@@ -13,6 +13,8 @@ public enum ValidationResult<Value> {
   case invalid(ValidationError)
 }
 
+extension ValidationResult: Sendable where Value: Sendable {}
+
 public extension ValidationResult {
   /// The validation error, or nil if the value is valid
   var error: ValidationError? {