build.yml: improve robustness

Author: wjakob

.github/workflows/build.yml

@@ -35,7 +35,9 @@ jobs:
 
       - name: Install dependencies on Linux
         if: runner.os == 'Linux'
-        run: sudo apt-get install -y xorg-dev libglu1-mesa-dev libwayland-dev libxkbcommon-dev libdbus-1-dev
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y xorg-dev libglu1-mesa-dev libwayland-dev libxkbcommon-dev libdbus-1-dev
 
       - name: Configure (Windows)
         if: runner.os == 'Windows'