chore(deps): update dependency system.runtime.serialization.formatters to v9

Author: renovate[bot]

src/Iesi.Collections/Iesi.Collections.csproj

@@ -29,7 +29,7 @@ Copyright © 2012 Oskar Berggren</Copyright>
 
   <ItemGroup Condition=" '$(TargetFramework)' == 'netstandard1.3' ">
     <PackageReference Include="System.Net.Http" Version="4.3.4" />
-    <PackageReference Include="System.Runtime.Serialization.Formatters" Version="4.3.0" />
+    <PackageReference Include="System.Runtime.Serialization.Formatters" Version="9.0.6" />
     <PackageReference Include="System.Text.RegularExpressions" Version="4.3.1" />
   </ItemGroup>