Fix: Skip tests correctly when ffmpeg is missing

tests/admin.test

@@ -17,7 +17,8 @@ L_PASS="bar"
 L_AUTH="$L_USER:$L_PASS"
 
 command -v ffmpeg >/dev/null 2>&1 || {
-    echo >&2 "# ffmpeg required for tests not found.  Aborting."; exit 1;
+    echo "1..0 # skip because ffmpeg is required but not present."
+    exit 0
 }
 
 echo "# Starting Icecast"