Format the src/_Derivatives submodule

[odow]

Following #2292, run the formatter over src/_Derivatives.

format("src/_Derivatives";
    margin = 80,
    always_for_in = true,
    remove_extra_newlines = true,
    always_use_return = true,
)

There are some `return nothing's that JuliaFormatter doesn't get rid of.

[codecov]

Codecov Report

Merging #2383 (6d96bcb) into master (a03543e) will increase coverage by 0.00%.
The diff coverage is 95.89%.

@@           Coverage Diff           @@
##           master    #2383   +/-   ##
=======================================
  Coverage   91.67%   91.67%           
=======================================
  Files          42       42           
  Lines        4442     4443    +1     
=======================================
+ Hits         4072     4073    +1     
  Misses        370      370           

Impacted Files	Coverage Δ
src/_Derivatives/_Derivatives.jl	100.00% <ø> (ø)
src/_Derivatives/forward.jl	97.78% <92.68%> (ø)
src/_Derivatives/coloring.jl	98.03% <93.82%> (ø)
src/_Derivatives/conversion.jl	98.11% <100.00%> (ø)
src/_Derivatives/linearity.jl	97.95% <100.00%> (ø)
src/_Derivatives/reverse.jl	93.47% <100.00%> (ø)
src/_Derivatives/sparsity.jl	97.56% <100.00%> (+0.03%)	⬆️
src/_Derivatives/subexpressions.jl	100.00% <100.00%> (ø)
src/_Derivatives/topological_sort.jl	100.00% <100.00%> (ø)
src/_Derivatives/types.jl	100.00% <100.00%> (ø)

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