- try to fix Github CI

Author: janbender

.github/workflows/build-linux.yml

@@ -11,6 +11,8 @@ jobs:
 
     steps:
     - uses: actions/checkout@v1
+    - name: apt-get update
+      run: sudo apt-get update --fix-missing
     - name: Install packages
       run: sudo apt-get -y install xorg-dev freeglut3-dev
     - name: configure