Release v0.42.0

Release v0.42.0rc0

Bump to 0.41.0 (jupyterlab#1204)

Bump to version 0.40.1 (jupyterlab#1192)

Bump to 0.40.0 (jupyterlab#1189)

Bump to 0.39.3 (jupyterlab#1173)

Bump node js version (jupyterlab#1174)

Bumping to 0.39.2 (jupyterlab#1164)

Bump to 0.39.1 (jupyterlab#1161)

Bump version to 0.39.0 (jupyterlab#1159)