Use `derive(FromPyObject)`

[kylebarron]

obstore/obstore/src/get.rs

Lines 37 to 38 in 7d7c928

	// Update to use derive(FromPyObject) when default is implemented:
	// https://github.com/PyO3/pyo3/issues/4643

I believe this is implemented now, and we've now upgraded to pyo3 0.27 #584

There are a couple locations of this