Update PyPlot example

[kimikage]

This changes the image format from PNG to SVG, and makes its colors dynamically set.

[codecov]

Codecov Report

Merging #415 into master will decrease coverage by 1.40%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #415      +/-   ##
==========================================
- Coverage   82.46%   81.06%   -1.41%     
==========================================
  Files          10       10              
  Lines         867      882      +15     
==========================================
  Hits          715      715              
- Misses        152      167      +15     

Impacted Files	Coverage Δ
src/utilities.jl	88.40% <0.00%> (-5.45%)	⬇️
src/algorithms.jl	59.81% <0.00%> (-2.94%)	⬇️
src/parse.jl	92.85% <0.00%> (-1.35%)	⬇️
src/display.jl	98.82% <0.00%> (-1.18%)	⬇️
src/differences.jl	31.46% <0.00%> (-0.91%)	⬇️

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[kimikage]

It looks like the sample numbers are different between the actual plot and the script.

and it is 0.9MB! 😅

docs/src/assets/figures/pyplot-seed-dcols.png PNG 1748x1026 1748x1026+0+0 8-bit sRGB 874257B

Of course, it is another option to generate the plot dynamically using PyPlot. However, the technical points of that example are to use the seed option and to convert the colors to arrays (cf. #298 (comment)), so I don't think the plotting result other than its colors is important.