Node.js app detected
-----> Build failed
 !     Two different lockfiles found: package-lock.json and yarn.lock
       Both npm and yarn have created lockfiles for this application,
       but only one can be used to install dependencies. Installing
       dependencies using the wrong package manager can result in missing
       packages or subtle bugs in production.
       - To use npm to install your application's dependencies please delete
         the yarn.lock file.
         $ git rm yarn.lock
       - To use yarn to install your application's dependences please delete
         the package-lock.json file.
         $ git rm package-lock.json

       https://kb.heroku.com/why-is-my-node-js-build-failing-because-of-conflicting-lock-files
 !     Push rejected, failed to compile Node.js app.
 !     Push failed