Different python versions in the containers for the integration tests

[davidwaroquiers]

Following discussion here: #255 (comment)

We could (should ?) adapt the containers so that the installed python version and environments matches the python version locally.

One question remains whether we need to test "combinations" of python versions (e.g. local runner daemon on python version 3.10 interacting with remote worker in which execution is done on python version 3.9). I feel it's a bit overkill but open to discuss.