Switch from karma-chai-sinon to karma-sinon-chai

[gavinr]

Describe the problem

This is the package we're currently using:

• karma-chai-sinon - 0.1.5 • Published 7 years ago

... seems like it is not well maintained.

Describe the proposed solution

It seems like this fork is better maintained:

• karma-sinon-chai - 2.0.2 • Published 4 years ago

Alternatives considered

No response

Additional Information

When I switch to karma-sinon-chai here though, the number of tests that get run goes from 311 to 253, so there's an issue there that we need to investigate why switching causes a drop in test cases that are run.