Add missing trailing slash in rsync command

[circlecube]

Proposed changes

The rsync command was missing the trailing slash so it wasn't properly copying build files into the npm dir. This should fix that and the module test workflow will reflect branch changes in js too now.

Type of Change

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation Update (if none of the other choices apply)

Checklist

• I have read the CONTRIBUTING doc
• Linting and tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)

Further comments