Update Travis CI configuration (#2536)
Update Travis CI configuration (#2536)

* Fix NPM deploy stage

* Fix Travis CI configuration file according to errors

... as seen in

- https://travis-ci.com/simple-icons/simple-icons/builds/147690404/config
- https://travis-ci.com/simple-icons/simple-icons/jobs/284138938/config

Note that `skip_cleanup` is no longer necessary according to https://docs.travis-ci.com/user/deployment-v2#cleaning-up-the-git-working-directory

simple-icons/simple-icons,simple-icons/simple-icons,danleech/simpleicons.org,danleech/simple-icons,danleech/simpleicons.org