Yarn upgrade (#2146)
Yarn upgrade (#2146)

Apologies if this means everyone has to `rm -rf node_modules`: react-ace
decided to turn some paths that were regular files into directories
and it turns out this really confuses yarn: https://github.com/securingsincity/react-ace/issues/1048
matrix-org/matrix-js-sdk,matrix-org/matrix-js-sdk,matrix-org/matrix-js-sdk,matrix-org/matrix-js-sdk