fix: do not execute on a child compilation

[alexander-akait]

This PR contains a:

• bugfix
• new feature
• code refactor
• test update
• typo fix
• metadata update

Motivation / Use-Case

fixes #505

Breaking Changes

No

Additional Info

No

[codecov]

Codecov Report

Merging #507 into master will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #507   +/-   ##
=======================================
  Coverage   97.52%   97.52%           
=======================================
  Files           8        8           
  Lines         202      202           
  Branches       55       55           
=======================================
  Hits          197      197           
  Misses          5        5           

Impacted Files	Coverage Δ
src/index.js	100.00% <100.00%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 6d51a69...db4cd75. Read the comment docs.

[alan-agius4]

@evilebottnawi, is there any chance of getting a release containing this fix cut soon? This is effecting us (the Angular team) in a bad way see angular/angular-cli#18087

[alexander-akait]

@alan-agius4 Yep, let's do it, want to solve #504 also in this patch, but it is not critical

[alexander-akait]

@alan-agius4 Done https://github.com/webpack-contrib/copy-webpack-plugin/releases/tag/v6.0.3

[alan-agius4]

Thanks @evilebottnawi