fix(ci): Fix "poetry could not find a pyproject.toml" in import lint workflow

[kdestin]

Description

This pull request fixes an issue with the import lint PR workflow, which errors out with message:

Poetry could not find a pyproject.toml file in /home/runner/work/promptflow/promptflow or its parents

All Promptflow Contribution checklist:

• The pull request does not introduce [breaking changes].
• CHANGELOG is updated for new features, bug fixes or other significant changes.
• I have read the contribution guidelines.
• I confirm that all new dependencies are compatible with the MIT license.
• Create an issue and link to the pull request to get dedicated review from promptflow team. Learn more: suggested workflow.

General Guidelines and Best Practices

• Title of the pull request is clear and informative.
• There are a small number of commits, each of which have an informative message. This means that previously merged commits do not appear in the history of the PR. For more information on cleaning up the commits in your PR, see this page.

Testing Guidelines

• Pull request includes test coverage for the included changes.

[kdestin]

Run fails with a separate error: https://github.com/microsoft/promptflow/actions/runs/12915843614/job/36018641808?pr=3935

  File "/home/runner/.cache/pypoetry/virtualenvs/promptflow-azure--uht9Cw5-py3.11/lib/python3.11/site-packages/azure/monitor/opentelemetry/_configure.py", line 25, in <module>
    from pkg_resources import iter_entry_points  # type: ignore
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
ModuleNotFoundError: No module named 'pkg_resources'	

A fix for this might've landed in azure-monitor-opentelemetry might've landed in 1.6.4
but an overly restrictive version requirement on azure-monitor-opentelemetry-exporter
is forcing poetry to resolve to 1.4.2. PR with fix: Azure/azure-sdk-for-python#39354