Relax the condition for dropping frames

This CL lowers the threshold for rounding up the frame timestamp from
0.5 frames to 0.45 frames.

Test: Record 240fps video with Google Camera and use framedrop.py to
analyze the file.

Bug: 68953930
Change-Id: Ibe739528a7363c5f2576bfdf658a101b95bf15f1