Python 2.7 tests are failing

[hkage]

Because of the ending Python 2.7 support, most of the CI images used for testing have dropped the Python 2.7 interpreter (and so setting up Python within the actions, see actions/setup-python#672). This leads to failing tests and breaks the testing chain for other Python versions. As our company still uses Python 2.7 for productive environments this project still needs to support Python 2.7.