fix 3d curvature calculation

[Nul1-Ptr]

Related issues

Closes #61

fix the 3D curvature calculation by adding $\Phi_{yz}$ term in numerator and changing the denominator to $(\Phi_x ^2 + \Phi_y ^2 + \Phi_z ^2)^{3/2}$

    elseif N == 3
        ϕx  = D⁰(ϕ, I, 1)
        ϕy  = D⁰(ϕ, I, 2)
        ϕz  = D⁰(ϕ, I, 3)
        ϕxx = D2⁰(ϕ, I, 1)
        ϕyy = D2⁰(ϕ, I, 2)
        ϕzz = D2⁰(ϕ, I, 3)
        ϕxy = D2(ϕ, I, (2, 1))
        ϕxz = D2(ϕ, I, (3, 1))
        ϕyz = D2(ϕ, I, (3, 2))
        κ   = (ϕxx * ϕy^2 + ϕyy * ϕx^2 + ϕxx * ϕz^2 + ϕzz * ϕx^2 + ϕyy * ϕz^2 + ϕzz  * ϕy^2 - 2 * ϕx * ϕz * ϕxz - 2 * ϕy * ϕz * ϕyz  - 2 * ϕy * ϕx * ϕxy) / (ϕx^2 + ϕy^2 + ϕz^2)^(3 / 2)
        return κ

Checklist

• I am following the contributing guidelines
• Tests are passing
• Lint workflow is passing
• Docs were updated and workflow is passing

[codecov]

Codecov Report

❌ Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 20.33%. Comparing base (ac86f34) to head (c69c725).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
src/levelset.jl	0.00%	2 Missing ⚠️

❗ There is a different number of reports uploaded between BASE (ac86f34) and HEAD (c69c725). Click for more details.

HEAD has 1 upload less than BASE

Flag	BASE (ac86f34)	HEAD (c69c725)
	2	1

Additional details and impacted files

@@             Coverage Diff             @@
##             main      #62       +/-   ##
===========================================
- Coverage   77.46%   20.33%   -57.13%     
===========================================
  Files          12       12               
  Lines         843      826       -17     
===========================================
- Hits          653      168      -485     
- Misses        190      658      +468     

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[maltezfaria]

Some minor formatting issues that I will handle later (I plan on switching the formatter to Runic in any case). Thanks for spotting the issue and for the fix!