DevOps: use python 3.10 in github workflows

[bastonero]

The latest versions of aiida-quantumespresso do not support
anymore python 3.9 as it is end-of-life. This made the weekly
workflow to fail.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.24%. Comparing base (ce961f8) to head (d8440ef).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #105   +/-   ##
=======================================
  Coverage   86.24%   86.24%           
=======================================
  Files          34       34           
  Lines        2567     2567           
=======================================
  Hits         2214     2214           
  Misses        353      353           

Flag	Coverage Δ
pytests	86.24% <ø> (ø)

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