Switches to use new context.extension

Updates CHANGELOG

trim-newlines is a transitive dependency which is present in a
dependency tree through imagemin-webp and node-sass.

Version of trim-newlines which is referenced by those pacakges has a
security advisory https://snyk.io/vuln/SNYK-JS-TRIMNEWLINES-1298042

Neither imagemin-webp nor node-sass have version which depend on patched
version of trim-newlines. And at least node-sass is not maintained any
longer.

Under current circumstances the only way to fix this is to force
trim-newlines version via "resolutions". As interface of the package is
backward compatible and does not break anything I believe it is a right
thing to do.

Changes from node-sass to sass