Stable orthogonalization

Description

In case the call to Cholesky fails, we now switch to Gram-Schmidt orthogonalization (for this call only). This avoid crashes of the code and makes it more stable.

News snippet

Making the Cholesky orthogonalization more stable.

Checklist

• I have checked that my code follows the Octopus coding standards
• I have added tests for all the new features added in this request.

changed milestone to %9.0

added Bug Core labels

Codecov Report

Merging #480 into develop will decrease coverage by <.01%. The diff coverage is 40%.

@@             Coverage Diff             @@
##           develop     #480      +/-   ##
===========================================
- Coverage    68.71%   68.71%   -0.01%     
===========================================
  Files          450      450              
  Lines        83186    83189       +3     
===========================================
+ Hits         57164    57165       +1     
- Misses       26022    26024       +2

Impacted Files	Coverage Δ
src/states/states_calc_inc.F90	74.92% <40%> (-0.18%)

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assigned to @micael.oliveira

merged