Update cmake-multi-platform.yml

Author: JunaMeinhold

.github/workflows/cmake-multi-platform.yml

@@ -41,7 +41,7 @@ jobs:
       if: matrix.os == 'ubuntu-latest'
       run: |
         sudo apt-get update
-        sudo apt-get install -y build-essential cmake
+        sudo apt-get install -y build-essential cmake libxrandr
 
     - name: Configure raylib with CMake
       run: |