Set package `__version__` attribute

[garrison]

With this:

$ python -c "import circuit_knitting; print(circuit_knitting.__version__)"
0.7.1

This essentially follows what we used to do at https://github.com/qiskit-community/quantum-prototype-template/blob/main/prototype_template/__init__.py.

[coveralls]

Pull Request Test Coverage Report for Build 8849774994

Details

• 5 of 5 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.006%) to 95.495%

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Totals
Change from base Build 8835676511:	0.006%
Covered Lines:	3498
Relevant Lines:	3663

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💛 - Coveralls