Bump Google.Protobuf from 3.10.0-rc1 to 3.15.0 in /src/XUnitTest_GrpcGreeterService#5

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dependabot/nuget/src/XUnitTest_GrpcGreeterService/Google.Protobuf-3.15.0P7CoreOrg/gRPC-dotnetcore-play:dependabot/nuget/src/XUnitTest_GrpcGreeterService/Google.Protobuf-3.15.0Copy head branch name to clipboard