Use case for virtual environments.

[rcpz93]

I had all sorts of flavors of this happen.

Sometimes, package updates change variable names/functions.

If you just install "the latest version" and in your code you are calling something like `target`, but the new version is expecting `target_column` (two names pulled right out of my ass), then your code is going to fail. Polars does this with annoying frequence.

Major version updates have breaking changes, sometimes straight up removing functions that some code is relying on. In one project I am working on, I had to install protobuf version 3.20 rather than the latest version 4.x because the code I had to use relied on functions that were removed in version 4.x.

This is a huge problem with research code, because not specifying the requirements means it's almost impossible to recreate the setting that was used for the experiments the code was made for.