perspective-jupyterlab not publishing to dist package

[timkpaine]

Was added here: fe68925#diff-9d8f23b3f4bb47ef250d6f6a116df908

Then you re-broke it here:
627ac48#diff-9d8f23b3f4bb47ef250d6f6a116df908

[texodus]

Thanks for the report! This has been "fixed" and was disted in 0.2.19, then superseded by #467