chore: use npm instead of Yarn in developer scripts

[RA80533]

Developers wishing to continue using Yarn on their local machines for development may continue to do so. Package installation, however, must be done via npm install.

[codecov]

Codecov Report

Merging #375 (8e28365) into master (bd60ae8) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #375   +/-   ##
=======================================
  Coverage   96.45%   96.45%           
=======================================
  Files           3        3           
  Lines         141      141           
  Branches       43       43           
=======================================
  Hits          136      136           
  Misses          5        5           

Flag	Coverage Δ
demo	87.50% <ø> (ø)
script	97.60% <ø> (ø)

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Impacted Files	Coverage Δ
src/buildExec.ts	97.60% <0.00%> (ø)

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