chore: Change deprecated pytest function

[Wonong]

Signed-off-by: Wonyeong Choi ciwnyg0815@gmail.com

Summary of Changes

Since the assertEquals function has been deprecated, replaced it with the assertEqual function for all test files.

Tests

Passed all existing unit tests

Documentation

pytest doc about deprecated function: https://docs.python.org/3.3/library/unittest.html#deprecated-aliases

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[feng-tao]

lgtm, thanks!