Version up to 21.6

Author: ManlyMarco

src/Common/Constants.cs

@@ -8,7 +8,7 @@ internal static class Constants
         /// Version number used by all plugins. Must be convertible to <see cref="System.Version"/>
         /// Uses ReleaseVersion.HotfixVersion format.
         /// </summary>
-        public const string PluginsVersion = "21.5.2";
+        public const string PluginsVersion = "21.6";
 
 #if AI
         internal static bool InsideStudio => Application.productName == StudioProcessName;