Deal II 9.7.1 available with significant changes from 9.6.0 to 9.7.0

[stefano2734]

New version to deal 9.6.0 is here in pipe.
But actual Version is 9.7.1.
See changes 9.6.0 to 9.7.0 in
https://dealii.org/developer/doxygen/deal.II/changes_between_9_6_0_and_9_7_0.html