[GRASS-git] [OSGeo/grass] 9342f4: CI: Switch Travis to Ubuntu 20.04 (focal) (#1384)

[Vaclav Petras]

  Branch: refs/heads/master
  Home:   https://github.com/OSGeo/grass
  Commit: 9342f4b6dd70565d52c8c1281a5ecc514efd778c
      https://github.com/OSGeo/grass/commit/9342f4b6dd70565d52c8c1281a5ecc514efd778c
  Author: Vaclav Petras <wenzeslaus at gmail.com>
  Date:   2021-02-19 (Fri, 19 Feb 2021)

  Changed paths:
    M .travis.yml
    M .travis/linux.install.sh

  Log Message:
  -----------
  CI: Switch Travis to Ubuntu 20.04 (focal) (#1384)

Switches to Ubuntu 20.04 (focal) in Travis and updates dependencies.

This makes it possible to have Python >=3.6 syntax in the source code without Travis build failing
(important for Black target-version py36 and above).