Upgrade MailKit and MimeKit to 4.16.0 to fix GHSA-9j88-vvj5-vhgr (#1270)

Issue #208413

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: claudiamurialdo

dotnet/src/dotnetcore/GxMail/GxMail.csproj

@@ -68,9 +68,9 @@
 
   <ItemGroup>
 	<PackageReference Include="Microsoft.Extensions.Configuration" Version="8.0.0" />
-    <PackageReference Include="MailKit" Version="4.15.1" />
+    <PackageReference Include="MailKit" Version="4.16.0" />
     <PackageReference Include="Microsoft.Exchange.WebServices" Version="2.2.0" />
-    <PackageReference Include="MimeKit" Version="4.15.1" />
+    <PackageReference Include="MimeKit" Version="4.16.0" />
     <PackageReference Include="Microsoft.Identity.Client" Version="4.61.3" />
     <PackageReference Include="OpenPop" Version="2.0.6.2" />
 	<PackageReference Include="Org.Mentalis.Security" Version="1.0.0" />

dotnet/src/dotnetframework/GxMail/GxMail.csproj

@@ -9,8 +9,8 @@
 	</PropertyGroup>
 
 	<ItemGroup>
-		<PackageReference Include="MailKit" Version="4.15.1" />
-		<PackageReference Include="MimeKit" Version="4.15.1" />
+		<PackageReference Include="MailKit" Version="4.16.0" />
+		<PackageReference Include="MimeKit" Version="4.16.0" />
 		<PackageReference Include="Microsoft.Identity.Client" Version="4.60.4" />
 		<PackageReference Include="OpenPop.NET" Version="2.0.6.1120" />
 		<PackageReference Include="Org.Mentalis.Security" Version="1.0.0" />