fix: remove pnpm cache from npm publish job

The publish-to-npm job downloads pre-built artifacts and doesn't check out
the full repository, so pnpm-lock.yaml is not available for caching.

Removed the cache parameter since it's not needed for publishing.

Author: saschabuehrle

.github/workflows/publish.yml

@@ -171,7 +171,6 @@ jobs:
         with:
           node-version: '20'
           registry-url: 'https://registry.npmjs.org'
-          cache: 'pnpm'
 
       - name: Publish @cascadeflow/core
         continue-on-error: true