[Snyk] Upgrade @material-ui/core from 3.8.1 to 3.9.4#2

hex22a wants to merge 1 commit intomastercrftd/rechner:masterfrom

snyk-upgrade-18ac07680a44521e9362d93f537462b9crftd/rechner:snyk-upgrade-18ac07680a44521e9362d93f537462b9Copy head branch name to clipboard