Signed-off-by: Ehud-Karavani <ehud.karavani@ibm.com>

Seems like there are no python builds on Ubuntu
https://raw.githubusercontent.com/actions/python-versions/main/versions-manifest.json

Don't cancel other the rest of the python version builds if only one (or more, just make them independent) fail.

It is not uncommon that only certain python versions fail due to dependency hell.

Since `hemm` failed due to no Pytorch

Also rename job

Test whether only one version succeeding is a matter of some resource parallel allocation mutex.

Revert the `fail-fast`, but now try to ensure that there are no parallel jobs by using `max-parallel`

Currently causes two main issues:
 - No `normalize` in `LinearRegression`.
   Easy, just need to update tests to use a Pipeline
 - Force singular feature type in pandas columns (harder)
    Harder, will require a safe-join mechanism when adding treatment as variable.

Workflow's name appear in the badge, so change that to a short `Build`
instead of a long "Build and install causallib".
Consequentially change the yml file from `test` to `build` to preserve
consistency

Signed-off-by: Ehud-Karavani <ehud.karavani@ibm.com>

Currently causes a problem with matplotlib when plotting `fill_between` in the calibration plot tests

Github Actions queue fix

Github Actions do not support python 3.6 on `ubuntu-latest`*, 
and since python 3.6 is well after its end of life, I see no use in hacking a way for it work.

Farewell python 3.6, you were great


*```
Error: The version '3.6' with architecture 'x64' was not found for Ubuntu 22.04.
The list of all available versions can be found here: https://raw.githubusercontent.com/actions/python-versions/main/versions-manifest.json
```

Signed-off-by: Ehud-Karavani <ehud.karavani@ibm.com>

Goodbye, Travis, thank you for your service.

Signed-off-by: Ehud-Karavani <ehud.karavani@ibm.com>

Check whether build now passes when removing the single process constraint and allowed to run in parallel