[CI] Swap to different source for Qt

.travis.yml

@@ -16,7 +16,6 @@ addons:
     sources:
       - ubuntu-toolchain-r-test
       - llvm-toolchain-trusty-4.0
-      - debian-sid
     packages:
       - clang-4.0
       - llvm-4.0-dev
@@ -26,12 +25,10 @@ addons:
       - libc++abi-dev
       - libglew-dev
       - libgtk-3-dev
-      - libpthread-stubs0-dev
       #- libvulkan1
       #- libvulkan-dev
       - libx11-dev
       - liblz4-dev
-      - qt5-default
 
 matrix:
   include:
@@ -45,6 +42,10 @@ git:
   submodules: false
 
 before_install:
+  # Qt
+  - sudo add-apt-repository -y ppa:ubuntu-sdk-team/ppa
+  - sudo apt-get update -yq
+  - sudo apt-get install qt5-default
   # Add Vulkan dependencies
   - travis_retry wget http://mirrors.kernel.org/ubuntu/pool/universe/v/vulkan/libvulkan1_$LIBVULKAN_VERSION+dfsg1-1ubuntu1~16.04.1_amd64.deb
   - travis_retry wget http://mirrors.kernel.org/ubuntu/pool/universe/v/vulkan/libvulkan-dev_$LIBVULKAN_VERSION+dfsg1-1ubuntu1~16.04.1_amd64.deb