math/saga: Update to 9.0.3

Bugfix release with some interesting fixes:

• never allow to unload a tool library, while any tool is running
• toolchains/ta_ls_factor.xml: inverted color ramp
• 3d_view_panel, mouse wheel rotation: zoom-in/out direction changed

Changelog: https://sourceforge.net/p/saga-gis/wiki/Changelog%209.0.3/attachment/changelog_saga_9.0.3.txt

MFH: 2023Q3