Improve custom equals fns

[woodsp-ibm]

Summary

In #225 I introduced a couple of custom equals functions. These were also added to ML in qiskit-community/qiskit-machine-learning#836 as the optimizers are locally copied there now. ML still runs mypy and it flagged issues with the equals implementation that this update addresses.

Details and comments

[coveralls]

Pull Request Test Coverage Report for Build 13954979262

Details

• 4 of 6 (66.67%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.02%) to 90.454%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
qiskit_algorithms/optimizers/gradient_descent.py	2	3	66.67%
qiskit_algorithms/optimizers/steppable_optimizer.py	2	3	66.67%

Totals
Change from base Build 13951776291:	-0.02%
Covered Lines:	6396
Relevant Lines:	7071

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💛 - Coveralls

[ElePT]

LGTM