Downgrade S.T.J to 8.0.3 (#381)

This is necessary so that dotnet/sdk can also downgrade back to 8.0.3. We can't update to 8.0.4 yet as we don't yet have a VS with binding redirects for msbuild on .NET Framework.

Author: ViktorHofer

eng/Versions.props

@@ -14,7 +14,7 @@
   </PropertyGroup>
   <PropertyGroup>
     <!-- Runtime dependencies -->
-    <SystemTextJsonVersion>8.0.4</SystemTextJsonVersion>
+    <SystemTextJsonVersion>8.0.0</SystemTextJsonVersion>
     <SystemSecurityCryptographyXmlVersion>8.0.0</SystemSecurityCryptographyXmlVersion>
     <!-- MSBuild dependencies -->
     <MicrosoftBuildTasksCoreVersion>17.8.3</MicrosoftBuildTasksCoreVersion>