Bump version to 9.1.0-preview-0004

Updated the project version in Directory.Build.props from 9.1.0-preview-0003 to 9.1.0-preview-0004 to reflect the latest changes. No other modifications were made.

Author: Richard Edwards

Directory.Build.props

@@ -1,6 +1,6 @@
 <Project>
 	<PropertyGroup>
-		<Version>9.1.0-preview-0003</Version>
+		<Version>9.1.0-preview-0004</Version>
 
 		<Nullable>enable</Nullable>
 		<WarningsAsErrors>nullable</WarningsAsErrors>