[libgxps] regtest: Fix png diff generation with python-pil pillow fork

[Carlos Garcia Campos <carlosgc src gnome org>]

commit e28a6c62a01ee89a4609515cb7dec5c80144ab03
Author: Carlos Garcia Campos <carlosgc gnome org>
Date:   Sun Feb 15 18:06:10 2015 +0100

    regtest: Fix png diff generation with python-pil pillow fork
    
    Use from PIL import Image instead of just import Image, since pillow
    only doesn't support import Image without using PIL.Image.

 regtest/Test.py |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/regtest/Test.py b/regtest/Test.py
index 5eb4ae9..fb86dbe 100644
--- a/regtest/Test.py
+++ b/regtest/Test.py
@@ -213,7 +213,7 @@ class Test:
 
     def _create_diff(self, ref_path, result_path):
         try:
-            import Image, ImageChops
+            from PIL import Image, ImageChops
         except ImportError:
             raise NotImplementedError