Update license file to note libbacktrace (#9579)
Update license file to note libbacktrace (#9579)

Co-authored-by: Tianqi Chen <78713c7adb79f9af6b43c2fcbfdd3866687ac7eb@users.noreply.github.com>
dmlc/tvm,Laurawly/tvm-1,dmlc/tvm,Laurawly/tvm-1,Laurawly/tvm-1,Laurawly/tvm-1,Laurawly/tvm-1,dmlc/tvm,dmlc/tvm,Laurawly/tvm-1,dmlc/tvm,Laurawly/tvm-1,Laurawly/tvm-1,Laurawly/tvm-1,dmlc/tvm,Laurawly/tvm-1,dmlc/tvm,dmlc/tvm,dmlc/tvm