[FEATURE REQUEST] Make `check-bot` check that base and alias have different values.

### I have searched through the issues and didn't find my problem.

- [X] Confirm

### Problem

Currently it's possible to add a new entry to `devicon.json` with the following code:
```json
"aliases": [
{
"base": "plain",
"alias": "plain"
}
]
```
Notice how the base and alias have the same value (`plain`). This does not make any sense, since the aliases attribute serves as a way to generate multiple font icon class name from just one SVG file ([ref the documentation for aliases](https://github.com/devicons/devicon/wiki/Updating-%60devicon.json%60#aliases-and-aliasobj)). So having plain as both an alias and base would only duplicate the class name.

Therefore we should make a check that fails if the base and alias are the same.

### Possible Solution

It should be possible to add an extra check to our existing `check-bot`, in this script: https://github.com/devicons/devicon/blob/master/.github/scripts/check_icon_pr.py

### Additional information

_No response_