Add 13.5+ to pre-installed Node.js versions

In our Organization projects, we depend on fresh node versions starting from 13.5+, within each build it taken from nvm. This process requires a network connection to node.js CDN, which not always reliable. Therefore sometimes we blocked by failing builds.

Downloading https://nodejs.org/dist/v13.5.0/node-v13.5.0.tar.xz...
No output has been received in the last 10m0s, this potentially indicates a stalled build or something wrong with the build itself.
Check the details on how to adjust your build configuration on: https://docs.travis-ci.com/user/common-build-problems/#build-times-out-because-no-output-was-received
The build has been terminated

Is it possible to add 13.5 or greater to pre-installed Node.js versions? Would much simplify our work, and less heat network overall.

The current preinstalled list is quite outdated
v10.15.3
v11.0.0
v4.9.1
v6.17.0
v8.12.0
v8.15.1
v8.9

Thank you in advance