Rename testem.js -> testem.cjs

Author: NullVoxPopuli

files/package.json

@@ -25,7 +25,7 @@
     "lint:js:fix": "eslint . --fix",<% if (typescript) { %>
     "lint:types": "glint",<% } %>
     "start": "vite dev",
-    "test": "vite build --mode=development && testem --file testem.js ci",
+    "test": "vite build --mode=development && testem --file testem.cjs ci",
     "prepack": "rollup --config"
   },
   "dependencies": {