Update travis script

Author: lolgab

.travis.yml

@@ -1,4 +1,5 @@
 os: linux
+dist: bionic
 language: scala
 stages:
   - name: test
@@ -14,8 +15,6 @@ jobs:
 
   - script: "./mill -j $(nproc) __.native.__.test"
     jdk: openjdk8
-    before_install:
-      - curl https://raw.githubusercontent.com/scala-native/scala-native/master/scripts/travis_setup.sh | bash -x
 
   - stage: release
     script: