Pixi pep508 file scheme does not support relative paths

[rmorshea]

Checks

• I have checked that this issue has not already been reported.

• I have confirmed this bug exists on the latest version of pixi, using pixi --version.

Reproducible example

Create a Python project with a dependency like

[project]
dependencies = ["my-package@file://./path/to/my-package-0.0.1-py3-none-any.whl"]

Running pixi i yields

  × Unsupported pep508 requirement: 'my-package@file://./path/to/my-package-0.0.1-py3-none-any.whl'
  ╰─▶ could not convert './path/to/my-package-0.0.1-py3-none-any.whl' to a file path

If I convert this to an absolute, rather than relative path installation succeeds.

[project]
dependencies = ["my-package@file:///absolute/path/to/my-package-0.0.1-py3-none-any.whl"]

This likely is resulting from an error in url.to_file_path.

Issue description

Pixi's method for converting pep508 file paths to requirements does not support relative paths.

Expected behavior

Pixi should be able to install packages via relative paths. This is currently an issue with pip but other tools have workarounds for the limitations in the pep508 spec. For example, Hatch has contextual formatting.