Check for orthogonality breakdown in Lanczos

[matteosecli]

Checklist

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Description

Check for breakdown of orthogonality and orthogonal initial vectors in the Lanczos solver.

Related issues or PRs

Fixes #501.

[codecov]

Codecov Report

Attention: Patch coverage is 76.47059% with 4 lines in your changes missing coverage. Please review.

Project coverage is 93.97%. Comparing base (3028fe0) to head (aca80ff).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/spectrum.jl	76.47%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #502      +/-   ##
==========================================
- Coverage   94.22%   93.97%   -0.25%     
==========================================
  Files          50       50              
  Lines        3412     3421       +9     
==========================================
  Hits         3215     3215              
- Misses        197      206       +9     

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[albertomercurio]

The code quality fails. I think you should use @warn "your text:

[matteosecli]

The code quality fails. I think you should use @warn "your text:

Oops 🙈