osc checkout throws python stack trace errors.  After initial login, it asks where to store the password.  Selecting Gnome Keyring or Transient generate Python stack trace errors (I did not test with Config option).

Here's an example output:
```
Your user account / password are not configured yet.
You will be asked for them below, and they will be stored in
/root/.config/osc/oscrc for future use.

Creating osc configuration file /root/.config/osc/oscrc ...
Username [api.opensuse.org]: vwbusguy
Password [vwbusguy.org]: 

NUM NAME              DESCRIPTION
1   Transient         Do not store the password and always ask for it [secure, in-memory]
2   Obfuscated config Store the password in obfuscated form in the osc config file [insecure, persistent]
3   Config            Store the password in plain text in the osc config file [insecure, persistent]
Select credentials manager [default=1]: 1
Traceback (most recent call last):
  File "/usr/lib/python3.12/site-packages/osc/commandline.py", line 418, in post_parse_args
    conf.get_config(
  File "/usr/lib/python3.12/site-packages/osc/conf.py", line 1823, in get_config
    raise oscerr.NoConfigfile(conffile, account_not_configured_text % conffile)
osc.oscerr.NoConfigfile: Config file cannot be found: /root/.config/osc/oscrc
   
Your user account / password are not configured yet.
You will be asked for them below, and they will be stored in
/root/.config/osc/oscrc for future use.


During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/bin/osc", line 33, in <module>
    sys.exit(load_entry_point('osc==1.4.4', 'console_scripts', 'osc')())
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/site-packages/osc/babysitter.py", line 226, in main
    sys.exit(run(commandline.OscMainCommand()))
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/site-packages/osc/babysitter.py", line 69, in run
    prg.main(argv)
  File "/usr/lib/python3.12/site-packages/osc/commandline.py", line 545, in main
    cmd.run(args)
  File "/usr/lib/python3.12/site-packages/osc/commandline.py", line 240, in run
    self.post_parse_args(args)
  File "/usr/lib/python3.12/site-packages/osc/commandline.py", line 433, in post_parse_args
    conf.interactive_config_setup(e.file, args.apiurl)
  File "/usr/lib/python3.12/site-packages/osc/conf.py", line 2009, in interactive_config_setup
    write_initial_config(conffile, config, creds_mgr_descriptor=creds_mgr_descr)
  File "/usr/lib/python3.12/site-packages/osc/conf.py", line 1719, in write_initial_config
    cp.readfp(sio)
    ^^^^^^^^^
AttributeError: 'OscConfigParser' object has no attribute 'readfp'. Did you mean: 'read'?
```

It seems the osc shipped in Fedora 39 isn't fully python 3.12 compatible.

Reproducible: Always

Steps to Reproduce:
1. Install osc
2. Attempt to osc checkout
3. Authenticate
4. Pick Gnome Keyring or Transient
Actual Results:  
osc crashes with a Python stack trace

Expected Results:  
osc stores credentials properly and completes the operation

I was able to reproduce this with or without python3-keyring installed.  I replicated it in Fedora 39 workstation and in a Fedora 39 container with podman.