fix a minor issue on test

[haihaolu]

An error is raised when running the test, because it does not reach the tolerance. Updating the iteraion limit resolves this issue.

Fixes #109

It's a good idea to open an issue first for discussion.

• [x] Tests pass
• [x] Appropriate changes to README are included in PR

[ohinder]

When I run the code currently all the tests pass

[dapplegate]

Followed up on comment from @ohinder in Issue #109.