Fix failing atan_rev test

[dpsanders]

No description provided.

[codecov-io]

Codecov Report

Merging #30 into master will decrease coverage by 42.84%.
The diff coverage is 100%.

@@             Coverage Diff             @@
##           master      #30       +/-   ##
===========================================
- Coverage   95.96%   53.12%   -42.85%     
===========================================
  Files           8       10        +2     
  Lines         124      224      +100     
===========================================
  Hits          119      119               
- Misses          5      105      +100

Impacted Files	Coverage Δ
src/inverse_trig.jl	40% <100%> (-60%)	⬇️
src/exponential.jl	53.57% <0%> (-46.43%)	⬇️
src/transformations.jl	54.16% <0%> (-45.84%)	⬇️
src/arithmetic.jl	34.54% <0%> (-44.63%)	⬇️
src/extrema.jl	83.33% <0%> (-16.67%)	⬇️
src/trig.jl	83.78% <0%> (-16.22%)	⬇️
src/powers.jl	0% <0%> (ø)
src/pave.jl	0% <0%> (ø)

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