Remove yarn from npm publish (#218)

https://yarnpkg.com/cli/npm/publish didn't work 

Moving this forward without bothering Raju this time.

Author: mikechu-optimizely

.github/workflows/react_release.yml

@@ -22,4 +22,4 @@ jobs:
     - name: Test, build, then publish
       env:
         NODE_AUTH_TOKEN: ${{ secrets.PUBLISH_REACT_SDK_TO_NPM }}
-      run: yarn npm publish
+      run: npm publish