Bump MimeKit from 4.13.0 to 4.15.1 (#660)

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

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HwProj.NotificationsService/HwProj.NotificationsService.API/HwProj.NotificationsService.API.csproj

@@ -12,7 +12,7 @@
   <ItemGroup>
     <PackageReference Include="MailKit" Version="4.13.0" />
     <PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer" Version="9.0.9" />
-    <PackageReference Include="MimeKit" Version="4.13.0" />
+    <PackageReference Include="MimeKit" Version="4.15.1" />
   </ItemGroup>
 
   <ItemGroup>