Update expected image following PIL->Pillow switch (bug 915742)

Fixes amo.tests.test_amo_utils:test_resize_transparency

The differences looks minimal, transparency is correctly conserved. I think it's just a subtle change in resize algorithm or something similar.

The test that fails with Pillow and the current existing image in master:

```
======================================================================
FAIL: apps.amo.tests.test_amo_utils.test_resize_transparency
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/dev/shm/jenkins.master/workspace/amo-master/venv/src/nose/nose/case.py", line 197, in runTest
    self.test(*self.arg)
  File "/dev/shm/jenkins.master/workspace/amo-master/apps/amo/tests/test_amo_utils.py", line 68, in test_resize_transparency
    assert dfh.read() == efh.read()
AssertionError
```