Bump MimeKit from 4.7.1 to 4.15.1

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

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

Author: dependabot[bot]

Fakemail.Core/Fakemail.Core.csproj

@@ -7,7 +7,7 @@
   <ItemGroup>
     <PackageReference Include="Microsoft.Extensions.Http" Version="8.0.0" />
     <PackageReference Include="Microsoft.Extensions.Logging" Version="8.0.0" />
-    <PackageReference Include="MimeKit" Version="4.7.1" />
+    <PackageReference Include="MimeKit" Version="4.15.1" />
     <PackageReference Include="System.IdentityModel.Tokens.Jwt" Version="7.6.3" />
   </ItemGroup>
 

Fakemail.Services.Tests/Fakemail.Services.Tests.csproj

@@ -9,7 +9,7 @@
 
   <ItemGroup>
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.10.0" />
-    <PackageReference Include="MimeKit" Version="4.7.1" />
+    <PackageReference Include="MimeKit" Version="4.15.1" />
     <PackageReference Include="xunit" Version="2.9.0" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.8.2">
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>