close(fig) broken for `subplots`

This works:

```julia
using PythonPlot

fig = figure()
close(fig)
```

this doesn't:

```julia
using PythonPlot

fig, ax = subplots()
close(fig)
```

```
ERROR: MethodError: no method matching close(::Py)
The function `close` exists, but no method is defined for this combination of argument types.

Closest candidates are:
close(::LibGit2.GitBranchIter)
@ LibGit2 ~/.julia/juliaup/julia-1.12.1+0.aarch64.apple.darwin14/share/julia/stdlib/v1.12/LibGit2/src/types.jl:1097
close(::LibGit2.GitTree)
@ LibGit2 ~/.julia/juliaup/julia-1.12.1+0.aarch64.apple.darwin14/share/julia/stdlib/v1.12/LibGit2/src/types.jl:1097
close(::LibGit2.GitRemote)
@ LibGit2 ~/.julia/juliaup/julia-1.12.1+0.aarch64.apple.darwin14/share/julia/stdlib/v1.12/LibGit2/src/types.jl:1097
...

Stacktrace:
[1] top-level scope
@ REPL[4]:1
[2] top-level scope
@ REPL:1
```

---

```
MacOS
Julia 1.12
PythonPlot v1.0.6
matplotlib v3.10.7
python v3.12.0
```