build: bump glib version requirement to 2.26.
build: bump glib version requirement to 2.26.

We already depends on some 2.26 features.

lu-zero/aravis,lu-zero/aravis,lu-zero/aravis,lu-zero/aravis,AravisProject/aravis,AravisProject/aravis,AnilRamachandran/aravis,AnilRamachandran/aravis,AnilRamachandran/aravis,AnilRamachandran/aravis,AravisProject/aravis,AravisProject/aravis,lu-zero/aravis,AravisProject/aravis,AnilRamachandran/aravis