qa: update xfstests version

qa: update xfstests version

Building xfstests on CentOS 8 has build errors:

    2020-01-23T21:15:14.939 INFO:tasks.workunit.client.0.smithi155.stderr:/home/ubuntu/cephtest/mnt.0/client.0/tmp/xfstests/src/fssum.c:616: undefined reference to `major'
    2020-01-23T21:15:14.939 INFO:tasks.workunit.client.0.smithi155.stderr:/home/ubuntu/cephtest/mnt.0/client.0/tmp/xfstests/src/fssum.c:617: undefined reference to `minor'
    2020-01-23T21:15:14.940 INFO:tasks.workunit.client.0.smithi155.stderr:collect2: error: ld returned 1 exit status

From: /ceph/teuthology-archive/pdonnell-2020-01-23_20:47:47-fs-wip-pdonnell-testing-20200122.210533-distro-basic-smithi/4697257/teuthology.log

Signed-off-by: Patrick Donnelly <pdonnell@redhat.com>