chore(dep): upgrade html-webpack-plugin to v4

[clarkdo]

No description provided.

[pi0]

Changelog: https://github.com/jantimon/html-webpack-plugin/blob/master/CHANGELOG.md#400-2020-03-23

Probably too soon to update in minor version. I would suggest waiting few days to ensure no regressions or merging to next.

[clarkdo]

@pi0 Is this OK now ? Latest version has been 4.3.0.

[codecov-io]

Codecov Report

Merging #7119 into dev will not change coverage.
The diff coverage is 0.00%.

@@           Coverage Diff           @@
##              dev    #7119   +/-   ##
=======================================
  Coverage   71.32%   71.32%           
=======================================
  Files          84       84           
  Lines        3431     3431           
  Branches      943      943           
=======================================
  Hits         2447     2447           
  Misses        794      794           
  Partials      190      190           

Flag	Coverage Δ
#unittests	71.32% <0.00%> (ø)

Impacted Files	Coverage Δ
packages/webpack/src/config/client.js	67.10% <ø> (ø)
packages/webpack/src/plugins/vue/modern.js	3.77% <0.00%> (ø)

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