Use poetry in tests of github workflow

[claudio-tw]

Context

the script run_tests.yaml installs the dependencies required by hisel using pip and the requirement file requirements-test.txt. This is not aligned to the intended management of the dependencies, which is via poetry. This PR proposes to unify these two approaches to dependence management, and it replaces the usage of pip and requirement files in the github tests with poetry commands.

Checklist

• [x] Change meets or does not compromise the Baseline Security Requirements