Assert Equals is Deprecated

[ardelato]

Description

When QAing https://github.com/danielbeardsley/cimpler/pull/114 , VSCode was giving me a warning about the usage of assert.equal in test/git-build.test.js as it has been deprecated for a while now. We should update the assert.equal declarations with the recommended assert.strictEqual declaration.

https://nodejs.org/api/assert.html#assert_assert_equal_actual_expected_message