chore: update MailKit to 4.15.1 to fix MimeKit vulnerability (GHSA-g7hc-96xr-gvvx) (#665)

Agent-Logs-Url: https://github.com/grandnode/grandnode2/sessions/0476c184-51f9-4c92-9d21-4e558e0b2140

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>

Author: Copilot

Directory.Packages.props

@@ -12,7 +12,7 @@
     <PackageVersion Include="Scalar.AspNetCore" Version="2.11.10" />
     <PackageVersion Include="Scryber.Core" Version="9.2.0.2" />
     <PackageVersion Include="Scryber.Core.OpenType" Version="9.2.0" />
-    <PackageVersion Include="MailKit" Version="4.14.1" />
+    <PackageVersion Include="MailKit" Version="4.15.1" />
     <PackageVersion Include="AWSSDK.Core" Version="4.0.3.6" />
     <PackageVersion Include="AWSSDK.S3" Version="4.0.16.1" />
     <PackageVersion Include="Azure.Storage.Blobs" Version="12.26.0" />