Bump Microsoft.AspNetCore.Server.Kestrel.Core from 2.1.3 to 2.1.7 (#1)

Bumps [Microsoft.AspNetCore.Server.Kestrel.Core](https://github.com/aspnet/AspNetCore) from 2.1.3 to 2.1.7.
- [Release notes](https://github.com/aspnet/AspNetCore/releases)
- [Changelog](https://github.com/dotnet/aspnetcore/blob/main/docs/ReleasePlanning.md)
- [Commits](https://github.com/aspnet/AspNetCore/compare/2.1.3...v2.1.7)

---
updated-dependencies:
- dependency-name: Microsoft.AspNetCore.Server.Kestrel.Core
  dependency-type: direct:production
...

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

kestrel.csproj

@@ -8,7 +8,7 @@
 
   <ItemGroup>
     <PackageReference Include="Microsoft.AspNetCore.Server.Kestrel" Version="2.1.3" />
-    <PackageReference Include="Microsoft.AspNetCore.Server.Kestrel.Core" Version="2.1.3" />
+    <PackageReference Include="Microsoft.AspNetCore.Server.Kestrel.Core" Version="2.1.7" />
     <PackageReference Include="Microsoft.AspNetCore.Server.Kestrel.Transport.Libuv" Version="2.1.3" />
     <PackageReference Include="Microsoft.AspNetCore.WebSockets" Version="2.1.7" />
   </ItemGroup>