Update azure-pipelines.yml

.azure/azure-pipelines.yml

@@ -5,6 +5,8 @@ strategy:
   matrix:
     linux-nightly:
       image: ubuntu-16.04
+        commands:
+          - sudo apt-get -y install libxcb-composite0-dev libx11-dev
     macos-nightly:
       image: macos-10.14
     windows-nightly:
@@ -18,7 +20,6 @@ steps:
       set -e
       curl https://sh.rustup.rs -sSf | sh -s -- -y --no-modify-path --default-toolchain `cat rust-toolchain`
       export PATH=$HOME/.cargo/bin:$PATH
-      sudo apt-get -y install libxcb-composite0-dev libx11-dev
       rustc -Vv
       echo "##vso[task.prependpath]$HOME/.cargo/bin"
       rustup component add rustfmt --toolchain `cat rust-toolchain`