ref: Handle old module.loaders syntax

[kamilogorek]

Fixes: #28 and #27

It's not deprecated and only "recommended" by official Webpack docs, so we should probably still support it - https://webpack.js.org/guides/migrating/#module-loaders-is-now-module-rules

[codecov-io]

Codecov Report

Merging #29 into master will decrease coverage by 2.7%.
The diff coverage is 0%.

@@            Coverage Diff             @@
##           master      #29      +/-   ##
==========================================
- Coverage   59.52%   56.81%   -2.71%     
==========================================
  Files           1        1              
  Lines          42       44       +2     
  Branches        8        9       +1     
==========================================
  Hits           25       25              
- Misses         12       13       +1     
- Partials        5        6       +1

Impacted Files	Coverage Δ
src/index.js	56.81% <0%> (-2.71%)	⬇️

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