Update build-linux.yml

Author: janbender

.github/workflows/build-linux.yml

@@ -9,6 +9,8 @@ jobs:
 
     steps:
     - uses: actions/checkout@v1
+    - name: Install glut
+      run: sudo apt-get -y install freeglut3-dev
     - name: configure
       run: mkdir build-release && cd build-release && cmake -DCMAKE_BUILD_TYPE=Release ..
     - name: build