Bump Python requirement imageio to 2.22.4

requirements.txt

 arkindex-client==1.0.11
 editdistance==0.6.1
 fontTools==4.38.0
-imageio==2.16.0
+imageio==2.22.4
 networkx==2.6.3
 numpy==1.22.3
 opencv-python==4.5.5.64