[41] Upgrade graphql-server to 3.0.0

[voj]

closes #41

The final 3.0.0 release had a slightly different structure.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (4f86dfb) to head (a99fa71).
⚠️ Report is 4 commits behind head on deploy-test.

Additional details and impacted files

@@              Coverage Diff              @@
##           deploy-test       #42   +/-   ##
=============================================
  Coverage       100.00%   100.00%           
=============================================
  Files                6         6           
  Lines              234       234           
  Branches            11        11           
=============================================
  Hits               234       234           

Flag	Coverage Δ
unittests	100.00% <ø> (ø)

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