chore: update Newtonsoft.Json to 13.0.3 (#113)

Author: ttu

JsonFlatFileDataStore/JsonFlatFileDataStore.csproj

@@ -32,7 +32,7 @@
 
   <ItemGroup>
     <PackageReference Include="Microsoft.CSharp" Version="4.7.0"/>
-    <PackageReference Include="Newtonsoft.Json" Version="13.0.2"/>
+    <PackageReference Include="Newtonsoft.Json" Version="13.0.3"/>
   </ItemGroup>
 
   <ItemGroup>