Add sphinx-rtd-theme dependency in setup

[protoroto]

Description

Add sphinx-rtd-theme dependency in setup

References

Fix #769

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

[coveralls]

coverage: 97.167%. remained the same when pulling 9438b22 on protoroto:bugfix/issue-769-add-sphinx-rtd-theme-dependency into 22e6cb1 on nephila:develop.

[codecov]

Codecov Report

All modified lines are covered by tests ✅

Comparison is base (22e6cb1) 94.38% compared to head (9438b22) 94.38%.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop     #770   +/-   ##
========================================
  Coverage    94.38%   94.38%           
========================================
  Files           26       26           
  Lines         1871     1871           
  Branches       266      266           
========================================
  Hits          1766     1766           
  Misses          53       53           
  Partials        52       52           

Flag	Coverage Δ
unittests	94.38% <ø> (ø)

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

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.