chore: Update manifest.json version to 4.0

Author: prvashisht

manifest.json

@@ -4,7 +4,7 @@
   "name": "SignatureSync: Pro Signatures",
   "short_name": "SignatureSync",
   "description": "Simplify your messaging with SignatureSync, the tool that automates your signatures, ensuring a professional touch every time.",
-  "version": "3.3",
+  "version": "4.0",
   "icons": {
     "16": "icons/light/icon16.png",
     "32": "icons/light/icon32.png",