WIP: use the harden_types branch from downstream ci

[mcocdawc]

from ecmwf/downstream-ci#70

Description

Contributor Declaration

By opening this pull request, I affirm the following:

• All authors agree to the Contributor License Agreement.
• The code follows the project's coding standards.
• I have performed self-review and added comments where needed.
• I have added or updated tests to verify that my changes are effective and functional.
• I have run all existing tests and confirmed they pass.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 56.32%. Comparing base (1817c31) to head (6a7729f).

Additional details and impacted files

@@           Coverage Diff            @@
##           develop      #45   +/-   ##
========================================
  Coverage    56.32%   56.32%           
========================================
  Files          618      618           
  Lines        25825    25825           
  Branches      2277     2277           
========================================
  Hits         14545    14545           
  Misses       11280    11280           

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