Make TEMPLATE_DIRS a tuple to make newer version of django happy
Make TEMPLATE_DIRS a tuple to make newer version of django happy

BUG=skia:3465

Review URL: https://codereview.chromium.org/968223003

google/skia-buildbot,google/skia-buildbot,Tiger66639/skia-buildbot,google/skia-buildbot,Tiger66639/skia-buildbot,google/skia-buildbot,Tiger66639/skia-buildbot,Tiger66639/skia-buildbot,google/skia-buildbot,google/skia-buildbot,Tiger66639/skia-buildbot,google/skia-buildbot,google/skia-buildbot,Tiger66639/skia-buildbot,Tiger66639/skia-buildbot