fix: Enhance content security policy to upgrade insecure requests

Author: jnton

manifest.json

@@ -12,7 +12,7 @@
     "https://*/*"
   ],
   "content_security_policy": {
-    "extension_pages": "script-src 'self'; object-src 'self';"
+    "extension_pages": "script-src 'self'; object-src 'self'; upgrade-insecure-requests;"
   },
   "background": {
     "service_worker": "background.js",