Fixing a poetry installation error in the pipeline

[aasheptunov]

Fixing a poetry installation error in the pipeline.

User story:
As a deveoper , I want to change the test execution workflow and fix Poetry version, so that to fix the error when running tests in a Python 3.9 environment.

DoD:

• The error type was investigated.
• The version of Poetry has been fixed to the latest version that supported Python 3.9.