Update System.Text.Json to 8.0.4 (#109)

Author: flobernd

src/Elastic.Transport/Elastic.Transport.csproj

@@ -35,7 +35,7 @@
   </ItemGroup>
 
   <ItemGroup Condition="'$(TargetFramework)' != 'net8.0'">
-    <PackageReference Include="System.Text.Json" Version="8.0.0" />
+    <PackageReference Include="System.Text.Json" Version="8.0.4" />
     <PackageReference Include="System.Diagnostics.DiagnosticSource" Version="8.0.0" />
   </ItemGroup>