CI: Start PulseAudio for Linux tests

Author: https://github.com/Zaggy1024
Commit: https://github.com/LadybirdBrowser/ladybird/commit/5063507fbbe
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/8689

.github/actions/setup/action.yml

@@ -98,6 +98,7 @@ runs:
             llvm-${{ inputs.llvm_version }} \
             nasm \
             ninja-build \
+            pulseaudio \
             qt6-base-dev \
             qt6-tools-dev-tools \
             tar \

.github/workflows/lagom-template.yml

@@ -188,6 +188,10 @@ jobs:
 
       # === TEST ===
 
+      - name: Start PulseAudio
+        if: ${{ inputs.os_name == 'Linux' }}
+        run: pulseaudio -D --exit-idle-time=1800 --load="module-null-sink sink_name=virtual_sink"
+
       - name: Test
         if: ${{ inputs.build_preset == 'Sanitizer' }}
         working-directory: ${{ github.workspace }}