[Snyk] Security upgrade webpack-dev-server from 3.9.0 to 3.11.0#11

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snyk-bot wants to merge 1 commit intomasterfrom snyk-fix-c4585afb51237373efce36439c819277

+330-209

Commits on Jul 9, 2020

fix: package.json & package-lock.json to reduce vulnerabilities
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