in-place replacement of sympy's analytical integration with scipy.integrate.quad

[dschick]

this looks something like:

lambda T: quad(self.heat_capacity[0], 0, T, limit=10000)[0]

need to add some testing and benchmarking

maybe it does not require a Warning anymore but just an informative message

It will be a replacement for #110 solving #108 and #109

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.15%. Comparing base (1d491dc) to head (8d284f0).

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #198      +/-   ##
===========================================
+ Coverage    86.13%   86.15%   +0.02%     
===========================================
  Files           10       10              
  Lines         3216     3221       +5     
===========================================
+ Hits          2770     2775       +5     
  Misses         446      446              

Files with missing lines	Coverage Δ
udkm1Dsim/structures/layers.py	88.15% <100.00%> (+0.13%)	⬆️

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[codspeed-hq]

Merging this PR will not alter performance

✅ 14 untouched benchmarks
⏩ 6 skipped benchmarks¹

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_{Comparing quad-in-function-str (8d284f0) with develop (1d491dc)}

Footnotes

1. 6 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩