Bump MimeKit from 4.14.0 to 4.15.1

---
updated-dependencies:
- dependency-name: MimeKit
  dependency-version: 4.15.1
  dependency-type: direct:production
...

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

Author: dependabot[bot]

Services/Lyralabs.TempMailServer.Services.csproj

@@ -11,7 +11,7 @@
         <PackageReference Include="Microsoft.Extensions.DependencyInjection.Abstractions" Version="10.0.1" />
         <PackageReference Include="Microsoft.Extensions.Hosting.Abstractions" Version="10.0.1" />
         <PackageReference Include="Microsoft.Extensions.Logging.Abstractions" Version="10.0.1" />
-        <PackageReference Include="MimeKit" Version="4.14.0" />
+        <PackageReference Include="MimeKit" Version="4.15.1" />
         <PackageReference Include="SmtpServer" Version="11.1.0" />
     </ItemGroup>