use bionic

.travis.yml

@@ -9,7 +9,7 @@ env:
   global:
   - USE_IRRKLANG: 1
 sudo: required
-dist: xenial
+dist: bionic
 osx_image: xcode9.4
 git:
   submodules: false
@@ -41,7 +41,7 @@ before_install:
 - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then mkdir irrlicht ; cd irrlicht ; curl --retry 5 --location https://github.com/moecube/irrlicht/releases/download/test/irrlicht-mycard-mac.tar.gz | tar zfx - ; cp libIrrlicht.a /usr/local/lib/ ; sudo cp -r include /usr/local/include/irrlicht ; cd .. ; fi
 
 - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then curl --retry 5 --location https://github.com/premake/premake-core/releases/download/v5.0.0-alpha12/premake-5.0.0-alpha12-macosx.tar.gz | tar zfx -; fi
-- if [[ "$TRAVIS_OS_NAME" == "linux" ]]; then curl --retry 5 --location https://github.com/premake/premake-core/releases/download/v5.0.0-alpha12/premake-5.0.0-alpha12-linux.tar.gz | tar zfx - ; fi
+- if [[ "$TRAVIS_OS_NAME" == "linux" ]]; then curl --retry 5 --location https://github.com/premake/premake-core/releases/download/v5.0.0-alpha13/premake-5.0.0-alpha13-linux.tar.gz | tar zfx - ; fi
 
 - git clone --depth=1 https://$IRRKLANG_ACCESS_KEY@github.com/purerosefallen/irrklang
 - mv -f irrklang/plugins/ikpmp3 .