math/saga: Update to 9.7.0

Release with several new features, tool updates, and bugfixes to
Clipper2, PostGIS raster, 3D View Panel, Proj, clipboard, Python ...

Changelog: https://sourceforge.net/p/saga-gis/wiki/Changelog%209.7.0/attachment/changelog_saga_9.7.0.txt

Reported by: portscout, Repology