MINOR: [C#] Bump Grpc.AspNetCore.Server from 2.67.0 to 2.71.0#47

dependabot[bot] wants to merge 1 commit intoupstreamsmellman/debian-apache-arrow:upstreamfrom

dependabot/nuget/csharp/src/Apache.Arrow.Flight.AspNetCore/Grpc.AspNetCore.Server-2.71.0smellman/debian-apache-arrow:dependabot/nuget/csharp/src/Apache.Arrow.Flight.AspNetCore/Grpc.AspNetCore.Server-2.71.0Copy head branch name to clipboard