Add support to pytest command

[yakky]

Description

Update runner.setup to be able to run tests via python -mpytest

References

Fix #167

Checklist

• I have read the contribution guide
• Code lint checked via inv lint
• changes file included (see docs)
• Usage documentation added in case of new features
• Tests added

[codecov]

Codecov Report

Merging #168 into develop will increase coverage by 0.07%.
The diff coverage is 96.55%.

@@             Coverage Diff             @@
##           develop     #168      +/-   ##
===========================================
+ Coverage    91.72%   91.80%   +0.07%     
===========================================
  Files            6        6              
  Lines          701      720      +19     
  Branches       115      119       +4     
===========================================
+ Hits           643      661      +18     
  Misses          20       20              
- Partials        38       39       +1     

Flag	Coverage Δ
#unittests	91.80% <96.55%> (+0.07%)	⬆️

Impacted Files	Coverage Δ
app_helper/runner.py	86.53% <90.90%> (+0.82%)	⬆️
app_helper/base_test.py	94.66% <100.00%> (+0.22%)	⬆️

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