Update JS dependencies

[silverwind]

• Update worker-loader options (currently unused pending Move eventsource.sharedworker to worker-loader #12459)
• Remove @babel/plugin-proposal-object-rest-spread, it's enabled by default
• Switch cssnano-webpack-plugin to css-minimizer-webpack-plugin which had been renamed

[codecov-commenter]

Codecov Report

Merging #12474 into master will increase coverage by 0.03%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master   #12474      +/-   ##
==========================================
+ Coverage   43.78%   43.82%   +0.03%     
==========================================
  Files         631      631              
  Lines       69851    69851              
==========================================
+ Hits        30587    30612      +25     
+ Misses      34330    34301      -29     
- Partials     4934     4938       +4     

Impacted Files	Coverage Δ
services/pull/temp_repo.go	32.97% <0.00%> (-3.20%)	⬇️
modules/log/event.go	57.54% <0.00%> (-1.89%)	⬇️
models/issue_comment.go	55.43% <0.00%> (+0.31%)	⬆️
services/pull/pull.go	43.87% <0.00%> (+0.46%)	⬆️
models/pull.go	55.17% <0.00%> (+0.62%)	⬆️
modules/git/repo.go	53.80% <0.00%> (+1.52%)	⬆️
modules/git/utils.go	77.04% <0.00%> (+3.27%)	⬆️
services/pull/check.go	56.15% <0.00%> (+16.15%)	⬆️

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[silverwind]

One more change added:

• Switch cssnano-webpack-plugin to css-minimizer-webpack-plugin which had been renamed

[sapk]

Sorry I restarted the failed build without re-checking that one as passed before inbeetween.