graphics/qgis-ltr: upgrade 3.4.5 -> 3.4.7

• Update several Python dependencies
• Add USE_PYQT=webkitwidgets for plugins like 'OpenLayers Plugin'
• Add USES=gnome, USE_GNOME=libxml2, USE_QT=gamepad, and LIB_DEPENDS=libsz.so:science/szip to pet 'make DEVELOPER=yes'
• Add OPTIONS_DEFAULT=SERVER
• Change files/patch-python_plugins_processing_algs_saga_SagaAlgorithmProvider.py to work with REQUIRED_VERSION
• Remove files/patch-python_plugins_processing_algs_saga_SagaUtils.py and files/patch-src_app_main.cpp, after they are upstream now
• Remove 'world writeable rights' in pkg-plist (not necessary)
• Update pkg-plist

PR: 237685
Submitted by: Rainer Hurling <rhurlin@gwdg.de> (maintainer)