ITS: loosen preview min frame rate ATOL

Bug: 318021850
Change-Id: Ie60ea2b684a91e0ee5d823caafadd0dbc96cd8e3
diff --git a/apps/CameraITS/tests/scene_flash/test_preview_min_frame_rate.py b/apps/CameraITS/tests/scene_flash/test_preview_min_frame_rate.py
index 122f951..835cef1 100644
--- a/apps/CameraITS/tests/scene_flash/test_preview_min_frame_rate.py
+++ b/apps/CameraITS/tests/scene_flash/test_preview_min_frame_rate.py
@@ -33,7 +33,7 @@
 _NAME = os.path.splitext(os.path.basename(__file__))[0]
 _PREVIEW_RECORDING_DURATION_SECONDS = 10
 _MAX_VAR_FRAME_DELTA = 0.001  # variance of frame deltas, units: seconds^2
-_FPS_ATOL = 0.5
+_FPS_ATOL = 0.8
 _DARKNESS_ATOL = 0.1 * 255  # openCV uses [0:255] images