Loosen tolerance on Bezier curve Newton solver

[gassmoeller]

The Newton iteration in the Bezier curve class can fail due to a too tight tolerance. 1e-15 seems to succeed.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (4539ca8) 92.80% compared to head (8dd2259) 92.46%.
Report is 40 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #647      +/-   ##
==========================================
- Coverage   92.80%   92.46%   -0.35%     
==========================================
  Files          92       92              
  Lines        6474     6500      +26     
==========================================
+ Hits         6008     6010       +2     
- Misses        466      490      +24     

Files	Coverage Δ
source/world_builder/objects/bezier_curve.cc	92.92% <100.00%> (ø)

... and 4 files with indirect coverage changes

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[github-actions]

Benchmark	Main	Feature	Difference (99.9% CI)
Slab interpolation simple none	1.019 ± 0.009 (s=441)	1.011 ± 0.008 (s=448)	-1.0% .. -0.7%
Slab interpolation curved simple none	1.015 ± 0.004 (s=451)	1.015 ± 0.006 (s=438)	-0.1% .. +0.1%
Spherical slab interpolation simple none	1.165 ± 0.007 (s=389)	1.164 ± 0.009 (s=386)	-0.3% .. +0.1%
Slab interpolation simple curved CMS	1.060 ± 0.005 (s=440)	1.059 ± 0.005 (s=412)	-0.2% .. +0.0%
Spherical slab interpolation simple CMS	1.589 ± 0.026 (s=295)	1.592 ± 0.027 (s=273)	-0.2% .. +0.7%
Spherical fault interpolation simple none	1.170 ± 0.005 (s=382)	1.169 ± 0.006 (s=390)	-0.2% .. +0.1%
Cartesian min max surface	2.293 ± 0.016 (s=187)	2.307 ± 0.034 (s=207)	+0.3% .. +1.0%
Spherical min max surface	7.213 ± 0.035 (s=72)	7.207 ± 0.032 (s=55)	-0.4% .. +0.2%