Rails / Travis - write permission ERROR on mac OS Catalina

I'm using Travis CI for a testing a rails app but it can't execute gem install bundler and it returns me the following logs:

resolvconf
services
3.07s$ sudo systemctl start redis-server
postgresql
2.98s$ travis_setup_postgresql 9.6
git.checkout
0.78s$ git clone --depth=50 --branch=master https://github.com/marcom86/product_hunt_clone.git marcom86/product_hunt_clone
0.01s
rvm
6.81s$ rvm use $(< .ruby-version) --install --binary --fuzzy
0.39s$ gem install bundler
Fetching: bundler-2.1.4.gem (100%)
ERROR:  While executing gem ... (Gem::FilePermissionError)
    You don't have write permissions for the /var/lib/gems/2.3.0 directory.
The command "gem install bundler" failed and exited with 1 during .
Your build has been stopped.

I think that is something related to mac OS Catalina pre-installed ruby 2.6, any workaround for this issued?