Add package serve to run a local server

wasm/package.json

@@ -4,6 +4,7 @@
   "description": "ffmpeg.wasm core",
   "main": "dist/ffmpeg-core.js",
   "scripts": {
+    "start": "serve .",
     "test": "node --experimental-wasm-threads --experimental-wasm-bulk-memory ./node_modules/.bin/jest"
   },
   "files": [
@@ -29,6 +30,7 @@
   },
   "homepage": "https://github.com/ffmpegwasm/FFmpeg#readme",
   "devDependencies": {
-    "jest": "^26.4.2"
+    "jest": "^26.4.2",
+    "serve": "^11.3.2"
   }
 }