chore: use manifest 2

src/manifest.json

@@ -1,10 +1,13 @@
 {
-  "manifest_version": 3,
+  "manifest_version": 2,
   "name": "Chrome Extension with React & Webpack",
   "background": {
-    "service_worker": "background.bundle.js"
+    "scripts": [
+      "background.bundle.js"
+    ],
+    "persistent": false
   },
-  "action": {
+  "browser_action": {
     "default_popup": "popup.html",
     "default_icon": "icon-34.png"
   },
@@ -12,10 +15,5 @@
     "128": "icon-128.png"
   },
   "permissions": ["scripting", "storage", "unlimitedStorage", "tabs"],
-  "web_accessible_resources": [
-    {
-      "resources": ["content.styles.css", "icon-128.png", "icon-34.png"],
-      "matches": []
-    }
-  ]
+  "web_accessible_resources": ["content.styles.css", "icon-128.png", "icon-34.png"]
 }