change signature threshold for accuracy

[oscar-davids]

What does this pull request do? Explain your changes. (required) change signature threshold for FV accuracy.

Specific updates (required)

How did you test each of these updates (required)

Does this pull request close any open issues?

Checklist:

• [x] Read the contribution guide
• [x] make runs successfully
• [x] All tests in ./test.sh pass
• [ ] README and other documentation updated
• [ ] Pending changelog updated