[Snyk] Upgrade source-map from 0.6.1 to 0.7.4#1

hex22a wants to merge 2 commits intomastercrftd/postcss:masterfrom

snyk-upgrade-2a132e0106f0f12add29deae8e768acbcrftd/postcss:snyk-upgrade-2a132e0106f0f12add29deae8e768acbCopy head branch name to clipboard