Parse requirements for testing

[JoranAngevaare]

What is the problem / what does the code in this PR do
Address #229

Can you briefly describe how it works?
Rather than figuring out e.g. numpy dependencies and compatibility in the requirements for strax, leave that to the base-environment (unless something is truly incompatible). Parse the requirements as set there (are tested against strax and straxen) such that we don't have to do it here.

The way we set it up now is cyclically unlogical, causing failures like: XENONnT/base_environment#444

This approach has been working perfectly for straxen:
XENONnT/straxen@bde58e9

[WenzDaniel]

I do not remember were the pandas and numpy requirements imposed by straxen?

[JoranAngevaare]

Nope, numpy was imposed since pip installed a pre-release of 1.20 which is incompatible with py36. Pandas was imposed in a similar way. There was a whole train of commits related to this in strax and straxen, which fueled my frustration: XENONnT/base_environment#404

This PR should put an end to this tuning of (in)compatibilities and leave such decisions to the user or dedicated software: https://github.com/XENONnT/base_environment/

We should here (in strax' requirements) just concern ourself with figuring out which version is compatible with the code rather than with what package and what not each dependency is compatible with.

[WenzDaniel]

We should here (in strax' requirements) just concern ourself with figuring out which version is compatible with the code rather than with what package and what not each dependency is compatible with.

Agreed, this is why I was asking.