Bump MailKit from 4.15.0 to 4.15.1

---
updated-dependencies:
- dependency-name: MailKit
  dependency-version: 4.15.1
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

SimpleMailArchiver/SimpleMailArchiver/SimpleMailArchiver.csproj

@@ -12,7 +12,7 @@
     <ItemGroup>
         <PackageReference Include="JetBrains.Annotations" Version="2025.2.4"/>
         <PackageReference Include="FluentResults" Version="4.0.0"/>
-        <PackageReference Include="MailKit" Version="4.15.0"/>
+        <PackageReference Include="MailKit" Version="4.15.1"/>
         <PackageReference Include="Microsoft.AspNetCore.Identity.EntityFrameworkCore" Version="10.0.3"/>
         <PackageReference Include="Microsoft.EntityFrameworkCore.Sqlite" Version="10.0.3"/>
         <PackageReference Include="Microsoft.EntityFrameworkCore.Tools" Version="10.0.3">