/bin/bash: line 1: uv: command not found

Question

I'm getting stuck during the build of my project - and I don't understand why ...

```bash
[stage-0 6/8] RUN --mount=type=cache,id=s/825c5fc2-52d8-45da-9350-e669d9490712-/root/cache/uv,target=/root/.cache/uv uv sync --extra production --frozen

✕ [stage-0 6/8] RUN --mount=type=cache,id=s/825c5fc2-52d8-45da-9350-e669d9490712-/root/cache/uv,target=/root/.cache/uv uv sync --extra production --frozen 
process "/bin/bash -ol pipefail -c uv sync --extra production --frozen" did not complete successfully: exit code: 127
```

With the following configuration:

`nixpacks.toml`
```toml
providers = ['python']

[variables]
NIXPACKS_UV_VERSION = "0.7.0"
NIXPACKS_PYTHON_PACKAGE_MANAGER = "uv"

[phases.install]
cmds = ["uv sync --extra production --frozen"]
```

`railway.toml`
```toml
# Documentation: https://docs.railway.com/reference/config-as-code#nixpacks-version
[build]
builder = "NIXPACKS"
# https://github.com/railwayapp/nixpacks/releases/
nixpacksVersion = "1.39.0"
nixpacksConfigPath = "./nixpacks.toml"

[build.nixpacksPlan]
providers = ["python"]
```

I'm quite puzzled ... Am I supposed to install `uv` by hand ? If then why setting `NIXPACKS_UV_VERSION`

Thanks for the help