Upgrade to Python3.9+ (update: already done in source.. release out of date)

I'm on Python 3.11.
In spatialmedia/gui.py I had to change

```
import tkFileDialog
import tkMessage
```

to

```
from tkinter import filedialog
from tkinter import tkmessage
```

and
`from TKinter import *`
to
`from tkinter import *`

and all 2 instances of `tkFileDialog` to `filedialog`
and all 1 instance of `tkMessageBox` to `messagebox`

Then in spatialdata/metadata_utils.py
I changed
`for child in parsed_xml.getchildren():`
to
`for child in parsed_xml: `