Please fix Install command for ubuntu on document

### Description

> In [Comprehensive Installation > Before Installing > Prerequisites ](https://scancode-toolkit.readthedocs.io/en/stable/getting-started/install.html#app-install), install command for ubuntu 16, 18, 20 ,22 and 24 is wrong.
On ubuntu we use python3-dev instead of python-dev. Please fix command line for Ubuntu.

#### wrong command

```bash
sudo apt install python-dev bzip2 xz-utils zlib1g libxml2-dev libxslt1-dev libpopt0
```
- Someone may look command for Ubuntu but not see it.
- because python-dev is missing, this generates some error.

#### right command

```bash
sudo apt install python3-dev bzip2 xz-utils zlib1g libxml2-dev libxslt1-dev libpopt0
```

- please use python3-dev for python3
- Just copy and paste it, run

### How To Reproduce

> Tell us how to reproduce the issue.

1. Go to [Comprehensive Installation > Before Installing > Prerequisites ](https://scancode-toolkit.readthedocs.io/en/stable/getting-started/install.html#app-install).
2. See that section.

### System configuration

> For bug reports, it really helps us to know:

* What OS are you running on? Ubuntu 24.04
* What version of scancode-toolkit was used to generate the scan file? latest package in Ubuntu (not effetced)
* What installation method was used to install/run scancode? apt