fix(docs): update Firefox version requirement in README

- Changed the Firefox version requirement from v135+ to v137+.
- Ensures users have the correct version for optimal functionality.

Author: amnweb

README.md

@@ -1,5 +1,5 @@
 # Firefox Plus (Windows only)
-> **Note:** FireFox v135+ only
+> **Note:** FireFox v137+ only
 
 <img src="screenshots/firefox-26-11-2023.jpg" alt="screenshot" title="Screenshot" width="900">
 <img src="screenshots/firefox-25-11-2023.jpg" alt="screenshot" title="Screenshot" width="900">