TST: make it possible to run tests without moto installed

[jorisvandenbossche]

No description provided.

[jreback]

a couple more

pandas/tests/io/conftest.py:import moto
pandas/tests/io/conftest.py:    moto.mock_s3().start()
pandas/tests/io/conftest.py:    moto.mock_s3().stop()
pandas/tests/io/json/test_compression.py:import moto
pandas/tests/io/json/test_compression.py:    with moto.mock_s3():
pandas/tests/io/test_excel.py:import moto
pandas/tests/io/test_excel.py:        with moto.mock_s3():

[jorisvandenbossche]

ah, yes, the difference is that this one is in a conftest, and so then even if you run some specific tests (not related to tests that use moto), it still tries to import it because it is in a conftest.py.

But will fix the others as well.

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[jreback]

thanks!