Increment stream version so we invalidate all existing streams.

src/Compilers/Core/Portable/Serialization/ObjectReader.cs

@@ -31,7 +31,7 @@ internal sealed partial class ObjectReader : IDisposable
         /// this version, just change VersionByte2.
         /// </summary>
         internal const byte VersionByte1 = 0b10101010;
-        internal const byte VersionByte2 = 0b00001000;
+        internal const byte VersionByte2 = 0b00001001;
 
         private readonly BinaryReader _reader;
         private readonly CancellationToken _cancellationToken;