CI: Ensure the build of SDL specific syscalls

Author: jserv

.github/workflows/main.yml

@@ -10,7 +10,7 @@ jobs:
     - name: install-dependencies
       run: |
             sudo apt-get update
-            sudo apt-get install libsdl2-dev
+            sudo apt-get install libsdl2-dev libsdl2-mixer-dev
             sh .ci/riscv-toolchain-install.sh
       shell: bash
     - name: default build