Change boundary condition for Windows PQC presence

Author: bartonjs

src/libraries/Common/tests/System/Security/Cryptography/AlgorithmImplementations/MLDsa/MLDsaTests.cs

@@ -35,7 +35,7 @@ public static void IsSupported_AgreesWithPlatform()
         }
 
         private static bool PlatformSupportsMLDsa() =>
-            PlatformDetection.IsOpenSsl3_5 || PlatformDetection.IsWindows10Version27858OrGreater;
+            PlatformDetection.IsOpenSsl3_5 || PlatformDetection.IsWindows10Version26200OrGreater;
 
         [Fact]
         public static void DisposeIsCalledOnImplementation()

src/libraries/Common/tests/System/Security/Cryptography/MLKemImplementationTests.cs

@@ -55,6 +55,6 @@ public static void IsSupported_AgreesWithPlatform()
 
         private static bool PlatformSupportsMLKem() =>
             PlatformDetection.IsOpenSsl3_5 ||
-            PlatformDetection.IsWindows10Version27858OrGreater;
+            PlatformDetection.IsWindows10Version26200OrGreater;
     }
 }

src/libraries/Common/tests/TestUtilities/System/PlatformDetection.Windows.cs

@@ -69,9 +69,8 @@ public static partial class PlatformDetection
         // Windows 11 aka 21H2
         public static bool IsWindows10Version22000OrGreater => IsWindowsVersionOrLater(10, 0, 22000);
 
-        // TODO: Update this to the first official PQC supported build when available.
-        // Windows 11 Insider Preview Build 27871 (Canary Channel)
-        public static bool IsWindows10Version27858OrGreater => IsWindowsVersionOrLater(10, 0, 27858);
+        // Windows 11 2025 Update (25H2)
+        public static bool IsWindows10Version26200OrGreater => IsWindowsVersionOrLater(10, 0, 26200);
 
         public static bool IsWindowsIoTCore
         {