Update output format from `get_sensitivity`

[Vaibhavdixit02]

Fixes #26

julia> sensres = get_sensitivity(prob, 100.0, y, pbounds)
Dict{Symbol, Float64} with 5 entries:
  :β_ST   => 0.877886
  :β_S1   => 0.022177
  :ρ_ST   => 0.93816
  :ρ_β_S2 => 0.977242
  :ρ_S1   => 0.0483608

[codecov[bot]]

Codecov Report

Merging #28 (f245091) into main (4b78623) will not change coverage. The diff coverage is 100.00%.

@@            Coverage Diff            @@
##              main       #28   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            1         1           
  Lines           24        35   +11     
=========================================
+ Hits            24        35   +11     

Impacted Files	Coverage Δ
src/EasyModelAnalysis.jl	100.00% <100.00%> (ø)

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[ChrisRackauckas]

Won't the indices sum to one?