fix npm dry run publish failures

[bfops]

Oddly it seems like a dry run release failed because the package is already published? maybe this is related to behavior changes in the npm version we recently upgraded to?

https://github.com/clockworklabs/SpacetimeDB/actions/runs/30608887839/job/91087144840

[bfops]

tl;dr I blame our recent upgrade our recent upgrade of npm in #5593. I think it now checks whether the package version is already published.