`import_from` is gone. Still in docs

[Documentation (dev)](https://juliapy.github.io/SymPy.jl/dev/reference/#SymPy.import_from-Union%7BTuple%7BAny%7D,%20Tuple%7BN%7D,%20Tuple%7BAny,%20Any%7D%7D%20where%20N) seems out of date.

It still lists the method `import_from` in the reference API,
but it's gone and not exported in `SymPyCore`.

Here is what I used to do (see #385)
```julia
begin
using SymPy
import PyCall
PyCall.pyimport_conda("sympy.physics.wigner", "sympy")
import_from(sympy.physics.wigner)
end
```

Now, it throws an error.
```
UndefVarError: `import_from` not defined in `Main.var"workspace#29"`
Suggestion: check for spelling errors or missing imports.
```

I was confused who suppose to export this method: `SymPy`, `SymPyCode`, or `PyCall`.

```julia
[91a5bcdd] Plots v1.40.13
[438e738f] PyCall v1.96.4
[24249f21] SymPy v2.3.3
[44cfe95a] Pkg v1.11.0
```