fix PyYAML warning on call of yaml.load(…)

[agebhar1]

Since PyYAML v5.1 a warning on deprecation is printed:

YAMLLoadWarning: calling yaml.load() without Loader=... is deprecated,
as the default Loader is unsafe. Please read https://msg.pyyaml.org/load
for full details.

Use the FullLoaders suggared variant yaml.full_load according to the
documentation [1] if it's present. Then it's assumed that PyYAML >= v5.1 is
used.

[1] https://github.com/yaml/pyyaml/wiki/PyYAML-yaml.load(input)-Deprecation#how-to-disable-the-warning

[coveralls]

Coverage remained the same at ?% when pulling f8751ca on agebhar1:feature/PyYAML5 into 4aa6fe9 on beerfactory:master.

[coveralls]

Coverage remained the same at ?% when pulling f8751ca on agebhar1:feature/PyYAML5 into 4aa6fe9 on beerfactory:master.