Add some more examples of package managers

[andrewgait]

https://github.com/UoMResearchIT/programming_with_python/blob/d0bf10d1adf272e13a351a15d63b04adf3b12645/episodes/04-software_package_management.md?plain=1#L27

This refers to venv and pip, but we could also mention e.g. uv, poetry etc. etc.

The grammar of this sentence also needs tidying up.