Adapt threshold to account for IMU constraints
Adapt threshold to account for IMU constraints

Summary:
One test fails due to the recently added IMU constraints.
- [Github Run 1](https://github.com/mapillary/OpenSfM/runs/4070087648?check_suite_focus=true)
- [Github Run 2](https://github.com/mapillary/OpenSfM/runs/4070078886?check_suite_focus=true)

{F676050021}

This diff relaxes the constraints a tiny bit

Reviewed By: paulinus

Differential Revision: D32095309

fbshipit-source-id: 40c6702b87409fe5e6af4a71a181c77d4f111c7f

mapillary/OpenSfM,mapillary/OpenSfM,mapillary/OpenSfM,mapillary/OpenSfM,mapillary/OpenSfM