Fix experimental flag usage

Author: pedrovgs

modules/wasm.py

@@ -595,7 +595,7 @@ def run_task_test():
                 "ALLOW_MEMORY_GROWTH=1",
                 "-s",
                 "FORCE_FILESYSTEM=1",
-                "--buildfs=opfs"
+                "--buildfs=opfs "
                 "--embed-file",
                 "assets/web-assembly.pdf",
             ]