plantuml,seleniumserver/test: fix pillow dependency

"image" is something else which depends on pillow, but also django,
which we don't need here.

software/plantuml/test/setup.py

@@ -46,6 +46,7 @@ setup(name=name,
         'slapos.libnetworkcache',
         'erp5.util',
         'supervisor',
+        'pillow',
         'psutil',
         'plantuml',
         'requests'

software/seleniumserver/test/setup.py

@@ -48,7 +48,7 @@ setup(
         'erp5.util',
         'selenium',
         'psutil',
-        'image',
+        'pillow',
         'requests',
         'paramiko',
     ],