Support git-style Python dependencies

### What problem are you facing?

I'd like to use git dependencies, e.g. for as-yet unreleased function-sdk-python builds. Unfortunately I can't because the build container doesn't have git installed.

```toml
dependencies = [
"crossplane-function-sdk-python @ git+https://github.com/negz/function-sdk-python.git@fb3968281747d4ee1f15b4f1eb14fec2a62c2326",
"click==8.3.2",
"grpcio>=1.73.1",
"crossplane-models @ file:./../../schemas/python",
]
```

### How could Crossplane help solve your problem?

Use a build container with `git` available.