fix: Fix indexing to use 1-based and use proper type in tests

[kshyatt-aws]

Issue #, if available: N/A

Description of changes: The Julia wrapper around Python lists is PyList. In the tests, we were constructing a raw Python list (which has type Py) and passing it to the extension method. This PR tightens up the acceptable types in the extension method and fixes the indexing.

Testing done: Unit tests passed locally.

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[kshyatt-aws]

Tested this with my local install of amazon-braket-simulator-v2-python and its unit tests passed too. To do the same edit juliapkg.json and make rev="ksh/index_fix".

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