Updated installation commands in README

[GuillaumeLeGoc]

In the current version of README, it creates a bare conda environment, without python nor pip. So the following pip install abba_python command uses the pip from conda base environment and installs abba_python in it, which might lead to conflicts in the user's conda base.

Notes :

• It should fix issue #10. doumazane said they were preparing a PR involving a conda .yaml environment file (which might be the way to go), but in the meantime, since the current instructions can lead to problems in users' conda instllation, here's a quick fix.
• This is my first PR so I basically have no idea what I'm doing, but I guess (hope) Github is smart enough to not let me break anything.
• Those are the commands I used to install latest abba_python which worked like a charm (so yes, python 3.10 works :) )

[NicoKiaru]

Thanks! Don't you think we need pip as well in this list ?

[GuillaumeLeGoc]

At least for me, with conda 23.10.0, creating an environment with python includes pip by default, but I guess it doesn't hurt to specify it.

[NicoKiaru]

Great, then if it doesn't hurt, please add pip and I'll merge your PR (and congrats if that's your first ;-)!)

[GuillaumeLeGoc]

And it's done ! (I think)