feat [WIP]: add strategy=lowest

[TiansuYu]

Pull Request Check List

Resolves: #3527

• Added tests for changed code.
• Updated documentation for changed code.

My comments

I have tried to follow the suggestion from here to come up with an solution. From what I have observed, it does not result in a resolution using the lowest version, but behaves the same as strategy=highest.

To reproduce, run poetry install then the dev version should be available at .venv/bin/poetry.

Try lock with an experiement project (e.g. with only one dependency, say requests):

.venv/bin/poetry lock --strategy=lowest --directory <some experimental project dir>

Then check what the result is, by poetry show --directory xyz (either using the dev one or a prod one):

certifi            2024.7.4 Python package for providing Mozilla's CA Bundle.
charset-normalizer 3.3.2    The Real First Universal Charset Detector. Open, modern...
idna               3.7      Internationalized Domain Names in Applications (IDNA)
requests           2.32.3   Python HTTP for Humans.
urllib3            2.2.2    HTTP library with thread-safe connection pooling, file ...

That means the native approach does not work. As a next step, I would have a deeper look at version_solver.py to understand if we could change the heuristics on version solving (not sure if I need to fully understand the Pubgrub algo though).

[Secrus]

Since you marked it as WIP, I converted the PR to draft.