Get rid of deprecation warnings in computational_resources.py

[danielhollas]

pytest test/test_computational_resources.py would generate 7 deprecation warnings coming from ipywidgets and traitlets.

Step towards fixing #490

[codecov]

Codecov Report

Patch coverage: 100.00% and project coverage change: +0.03% 🎉

Comparison is base (5038966) 79.42% compared to head (1c41819) 79.46%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #508      +/-   ##
==========================================
+ Coverage   79.42%   79.46%   +0.03%     
==========================================
  Files          27       27              
  Lines        3757     3759       +2     
==========================================
+ Hits         2984     2987       +3     
+ Misses        773      772       -1     

Flag	Coverage Δ
python-3.10	79.46% <100.00%> (+0.03%)	⬆️
python-3.8	79.49% <100.00%> (+0.03%)	⬆️
python-3.9	79.49% <100.00%> (+0.03%)	⬆️

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

Files Changed	Coverage Δ
aiidalab_widgets_base/databases.py	94.11% <ø> (+0.65%)	⬆️
aiidalab_widgets_base/computational_resources.py	70.66% <100.00%> (+0.10%)	⬆️
tests/test_computational_resources.py	100.00% <100.00%> (ø)

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[yakutovicha]

LGTM