Adopt lazy imports from Terra (backport #152)

[mergify]

This is an automatic backport of pull request #152 done by Mergify.
Cherry-pick of 63822de has failed:

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Changes to be committed:
	modified:   qiskit_finance/data_providers/random_data_provider.py
	modified:   qiskit_finance/data_providers/yahoo_data_provider.py
	modified:   requirements.txt
	modified:   test/__init__.py
	modified:   test/circuit/test_european_call_delta_objective.py
	modified:   test/circuit/test_european_call_pricing_objective.py
	modified:   test/circuit/test_fixed_income_pricing_objective.py
	modified:   test/data_providers/test_data_providers.py
	modified:   test/finance_test_case.py

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   qiskit_finance/data_providers/exchange_data_provider.py
	both modified:   qiskit_finance/data_providers/wikipedia_data_provider.py

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/github/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

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[coveralls]

Pull Request Test Coverage Report for Build 2952136461

• 2 of 2 (100.0%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.4%) to 83.017%

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Totals
Change from base Build 2951997411:	0.4%
Covered Lines:	699
Relevant Lines:	842

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💛 - Coveralls