Fix Travis CI Warnings

[mkasberg]

Travis CI is producing some warning and info messages on our builds: https://travis-ci.org/github/mkasberg/script-seed/jobs/733535031/config

Let's fix all of these by editing the .travis.yml file at the root of this repository. Here are the docs: https://docs.travis-ci.com/user/customizing-the-build/

• Remove the sudo key since it no longer does anything.
• Set the dist to the latest LTS version of Ubuntu: focal https://docs.travis-ci.com/user/reference/focal/
• Set os to linux to make that warning go away.
• Set the language to minimal: https://docs.travis-ci.com/user/languages/minimal-and-generic/

[ry-v1]

Can I take up this?

[mkasberg]

Yes, please do!

[ry-v1]

Submitted pull request #40. Please check.