retrieve prebuild phase diagrams from OpenData

[tschaume]

see https://matsci.org/t/inquiry-regarding-discrepancy-in-phase-diagram-data-from-api-and-web-interface/60035/2

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 66.57%. Comparing base (0786122) to head (65c3092).
Report is 25 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #961      +/-   ##
==========================================
- Coverage   67.51%   66.57%   -0.95%     
==========================================
  Files          49       49              
  Lines        2543     2606      +63     
==========================================
+ Hits         1717     1735      +18     
- Misses        826      871      +45     

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