fix `(+python/open-ipython-repl)` fails opening ipython since it invoke python

### I confirm that...

- [x] I have searched the [issue tracker](https://github.com/doomemacs/doomemacs/issues), [documentation](https://docs.doomemacs.org), [FAQ](https://docs.doomemacs.org/-/faq), [Discourse](https://discourse.doomemacs.org), and [Google](https://google.com), in case this issue has already been reported/resolved.

- [x] I have read "[How to Debug Issues](https://doomemacs.org/d/how2debug)", and will use it to provide as much information about this issue as possible.

- [x] The issue can be reproduced on the **latest** available commit of Doom.

- [x] The issue can be reproduced on a stable release of Emacs, such as 27, 28, or 29. *(Unstable versions end in .50, .60, or .9x)*

### Expected behavior

+python/open-ipython-repl should open a new buffer with ipython but it fails because it uses the executable `python` instead of `ipython`.

### Current behavior

+python/open-ipython-repl tries to open a buffer with the argument of `ipython` concatenated to the executable `python`

### Steps to reproduce

Invoke `+python/open-ipython-repl` from a regular directory ie. outside of a pipenv or conda project.

this pull request should fix the issue:
https://github.com/doomemacs/doomemacs/pull/8126

### System Information

https://gist.github.com/emiltoacs/b59f0c67130373b7808a41fea79a1d7b