Update the CI to test Daiquiri package instead of the source

Following comments on !436 (merged)

Here is the changes:

1. This change make sure to test the installed version on Daiquiri, instead of testing the local source. This makes sure the package is self independent and nothing is missing inside.

2. A setuptools helper was added to deal with tag version. The result is a bit different than before, but i prefer to delegate that stuff to a third party, and have a setup.py empty.

$ python -c 'import daiquiri; print(daiquiri.__version__)'
0.1.dev1436+g4ad725d.d20220120
$ python -c 'import daiquiri; print(daiquiri.version_info)
(0, 1, 'dev1436', 'g4ad725d.d20220120')

3. Instead of save_spec a save_spec_file is used to request the JSON descriiption of the API. This allow to remove the location of the project documentation from the Daiquiri package. This location is now provided by the dedicated tests/fixture