Update installation.md

Some shells (like zsh) require quotes to avoid attempting to interpret the square braces.

Author: maxarai

docs/docs/usage/getting_started/installation.md

@@ -27,5 +27,5 @@ this will install the default version of [PyTorch](https://pytorch.org/) for you
 :::
 
 ``` bash
-pip install pymusas[neural]
-```
+pip install 'pymusas[neural]'
+```