Misalignment of first line in multiline show of PyObject

PyObjects whose pystring method returns a multiline string have their first row misaligned when shown. For example

```julia
using PyCall
qiskit = pyimport("qiskit")
qc = qiskit.QuantumCircuit(1)
qc.x(0)
qc.draw()
```
gives
```
PyObject ┌───┐
q_0: ┤ X ├
└───┘
```

A fix would be to replace
```julia
function show(io::IO, o::PyObject)
print(io, "PyObject $(pystring(o))")
end
```
with
```julia
function show(io::IO, o::PyObject)
str = pystring(o)
sep = contains(str, "\n") ? "\n" : " " # Avoid misaligning the first line for multiline prints
print(io, "PyObject$sep$str")
end
```
which gives the following print instead.
```
PyObject
┌───┐
q_0: ┤ X ├
└───┘
```

Start at the show(io::IO, o::PyObject) implementation and reproduce the issue with a PyObject whose pystring result contains newlines, using the provided qiskit example. Verify that single-line output keeps its spacing while multiline output places PyObject on its own line and no longer misaligns the first row.

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