Update dependency MailKit to 4.9.0

Author: renovate[bot]

Jellyfin.Plugin.Webhook/Jellyfin.Plugin.Webhook.csproj

@@ -12,7 +12,7 @@
 
     <ItemGroup>
       <PackageReference Include="Jellyfin.Controller" Version="10.*-*" />
-      <PackageReference Include="MailKit" Version="4.8.0" />
+      <PackageReference Include="MailKit" Version="4.9.0" />
       <PackageReference Include="Handlebars.Net" Version="2.1.6" />
       <PackageReference Include="Microsoft.Extensions.Http" Version="8.0.1" />
       <PackageReference Include="MQTTnet.Extensions.ManagedClient" Version="4.3.7.1207" />