Fix: adjust respack config to fix hmr

[hammisaad]

Closes #161

Developer Checklist (Definition of Done)

Issue

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Summary of changes

• see "Refused to apply style from ... because its MIME type" error webpack/webpack-dev-server#3168 (comment) for solution, apparently the css plugins can't handle HMR with hashes: HMR: inferring script source from moduleId is not reliable and don't work with [hash]/[fullhash] webpack/mini-css-extract-plugin#444

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