Update test commands in package.json to use npx for web-test-runner, ensuring consistent execution across environments.

Author: alexpmule

package.json

@@ -62,8 +62,8 @@
     "lint:types": "tsc",
     "lint": "npm run lint:eslint",
     "format": "npm run format:eslint",
-    "test": "web-test-runner test/**/*.test.js --coverage --node-resolve --playwright --browsers chromium firefox webkit",
-    "test:watch": "web-test-runner test/**/*.test.js --node-resolve --watch --playwright --browsers chromium",
+    "test": "npx web-test-runner test/**/*.test.js --coverage --node-resolve --playwright --browsers chromium firefox webkit",
+    "test:watch": "npx web-test-runner test/**/*.test.js --node-resolve --watch --playwright --browsers chromium",
     "gen:wc": "wca analyze \"*.js\" --outFile custom-elements.json",
     "prepare": "node demo/model.js"
   },