pynodegl: factor out dict update function
pynodegl: factor out dict update function

nodes_def.pyx:         2603 ->  2546 (lines)
pynodegl.c:           69431 -> 68401 (lines)
pynodegl.so (x86_64):  609K ->  605K

gopro/gopro-lib-node.gl,gopro/gopro-lib-node.gl,gopro/gopro-lib-node.gl,gopro/gopro-lib-node.gl