🐛 fixes unhandled exception when parsing an invalid string

[pcrespov]

What do these changes do?

An unhandled exception is causing the director service to respond with 500 every time is requested to list running services services.

The exception displayed ValueError: unconverted data remains: Z and was raised while parsing an invalid string into a datetime.

A new utils with a more robust parse_as_datetime routine was implemented. In case of an invalid string, the function will return a default provided in the arguments.

Related issue/s

None.

How to test

NOTE: needs python 3.6 in place (e.g. use pyenv local )
NOTE: avoid using make install-dev, since it was not adapted properly since this service will be soon removed

make devenv
cd services/director
pip install -e .
pytest tests/unit/test_utils.py

[codecov]

Codecov Report

Merging #2608 (8e378b5) into master (0446da5) will increase coverage by 0.0%.
The diff coverage is 100.0%.

@@          Coverage Diff           @@
##           master   #2608   +/-   ##
======================================
  Coverage    76.9%   77.0%           
======================================
  Files         630     631    +1     
  Lines       24741   24752   +11     
  Branches     2430    2430           
======================================
+ Hits        19043   19071   +28     
+ Misses       5050    5039   -11     
+ Partials      648     642    -6     

Flag	Coverage Δ
integrationtests	66.6% <ø> (+<0.1%)	⬆️
unittests	71.5% <100.0%> (+<0.1%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
.../director/src/simcore_service_director/producer.py	61.2% <100.0%> (-0.5%)	⬇️
...ces/director/src/simcore_service_director/utils.py	100.0% <100.0%> (ø)
...simcore_service_webserver/projects/projects_api.py	84.8% <0.0%> (+0.3%)	⬆️
...ce_webserver/resource_manager/garbage_collector.py	74.3% <0.0%> (+0.8%)	⬆️
...ector_v2/modules/dynamic_sidecar/scheduler/task.py	92.2% <0.0%> (+1.6%)	⬆️
...simcore_service_director_v2/modules/dask_client.py	92.5% <0.0%> (+1.6%)	⬆️
...rvice_dynamic_sidecar/modules/directory_watcher.py	94.4% <0.0%> (+1.8%)	⬆️
...s/dynamic_sidecar/docker_service_specs/settings.py	75.0% <0.0%> (+2.5%)	⬆️
...webserver/computation_comp_tasks_listening_task.py	85.7% <0.0%> (+3.0%)	⬆️