pycall api updates

PyCall 1.90.0 is now released, which change `o[:foo]` and `o["foo"]` to `o.foo` and `o."foo"`, respectively, for python objects `o`; see also JuliaPy/PyCall.jl#629.

The old `getindex` methods still work but are deprecated, so you'll want to put out a new release that uses the new methods and REQUIREs PyCall 1.90.0 to avoid having zillions of deprecation messages.

Start by reviewing the PyCall 1.90.0 release and JuliaPy/PyCall.jl#629, then locate this package's uses of the deprecated getindex methods and its REQUIRE file. Done means the package uses the new PyCall access methods, requires PyCall 1.90.0, and has a new release.

Scritto dal modello di indicizzazione a partire dal testo della issue.