Trim off a few more dependencies

[saethlin]

Per #139

[codecov]

Codecov Report

Merging #188 into master will decrease coverage by 0.34%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #188      +/-   ##
==========================================
- Coverage   90.65%   90.31%   -0.35%     
==========================================
  Files          17       17              
  Lines        2311     2219      -92     
==========================================
- Hits         2095     2004      -91     
+ Misses        216      215       -1     

Impacted Files	Coverage Δ
src/collapse/common.rs	62.83% <100.00%> (-0.04%)	⬇️
src/flamegraph/rand.rs	94.87% <0.00%> (-2.57%)	⬇️
src/flamegraph/color/palettes.rs	99.53% <0.00%> (-0.13%)	⬇️
src/flamegraph/svg.rs	97.76% <0.00%> (-0.10%)	⬇️
src/flamegraph/merge.rs	94.73% <0.00%> (-0.06%)	⬇️
src/flamegraph/mod.rs	96.41% <0.00%> (-0.06%)	⬇️
src/differential/mod.rs	98.33% <0.00%> (-0.03%)	⬇️
src/flamegraph/color/mod.rs	82.51% <0.00%> (+0.69%)	⬆️

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[jonhoo]

That's excellent, thank you!

[jonhoo]

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