Update source map loader dependency

[KaneFreeman]

Type: bug / feature

The following has been addressed in the PR:

• There is a related issue
• All code has been formatted with prettier
• Unit or Functional tests are included in the PR
• schema.json has been updated appopriately

Description:
Update from custom source-map-loader-cli dependency to official source-map-loader

Before

After

Resolves #429

[codecov]

Codecov Report

Merging #470 (fc57964) into master (7b72a3f) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #470   +/-   ##
=======================================
  Coverage   43.50%   43.50%           
=======================================
  Files          12       12           
  Lines         878      878           
  Branches      265      265           
=======================================
  Hits          382      382           
  Misses        496      496           

Impacted Files	Coverage Δ
src/base.config.ts	19.24% <ø> (ø)

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[agubler]

Can we pin this please