Minor Keyword Argument Fix with 𝔼

[pulsipher]

This fixes a bug that 𝔼 didn't accept the pdf keyword

[codecov]

Codecov Report

Merging #191 (d9bfa6f) into master (304ea6c) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #191   +/-   ##
=======================================
  Coverage   99.81%   99.81%           
=======================================
  Files          33       33           
  Lines        7074     7074           
=======================================
  Hits         7061     7061           
  Misses         13       13           

Impacted Files	Coverage Δ
src/MeasureToolbox/expectations.jl	94.20% <100.00%> (ø)

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