Update README + fix bug for GPU total memory

Author: mathoudebine

README.md

@@ -9,7 +9,7 @@ This project is an open-source alternative software, NOT the original software p
 * for other smart screens, contact your reseller
 ---
 
-![Linux](https://img.shields.io/badge/Linux-FCC624?style=for-the-badge&logo=linux&logoColor=black) ![Windows](https://img.shields.io/badge/Windows-0078D6?style=for-the-badge&logo=windows&logoColor=white) ![macOS](https://img.shields.io/badge/mac%20os-000000?style=for-the-badge&logo=apple&logoColor=white) ![Raspberry Pi](https://img.shields.io/badge/Raspberry%20Pi-A22846?style=for-the-badge&logo=Raspberry%20Pi&logoColor=white) ![Python](https://img.shields.io/badge/Python-3.8/3.12-3670A0?style=for-the-badge&logo=python&logoColor=ffdd54) [![Licence](https://img.shields.io/github/license/mathoudebine/turing-smart-screen-python?style=for-the-badge)](./LICENSE)
+![Linux](https://img.shields.io/badge/Linux-FCC624?style=for-the-badge&logo=linux&logoColor=black) ![Windows](https://img.shields.io/badge/Windows-0078D6?style=for-the-badge&logo=windows&logoColor=white) ![macOS](https://img.shields.io/badge/mac%20os-000000?style=for-the-badge&logo=apple&logoColor=white) ![Raspberry Pi](https://img.shields.io/badge/Raspberry%20Pi-A22846?style=for-the-badge&logo=Raspberry%20Pi&logoColor=white) ![Python](https://img.shields.io/badge/Python-3.8/3.13-3670A0?style=for-the-badge&logo=python&logoColor=ffdd54) [![Licence](https://img.shields.io/github/license/mathoudebine/turing-smart-screen-python?style=for-the-badge)](./LICENSE)
 
 
 A Python system monitor program and an abstraction library for **small IPS USB-C (UART) displays.**    

library/stats.py

@@ -476,8 +476,8 @@ def stats(cls):
 
         # GPU mem. total memory (M)
         gpu_mem_total_text_data = theme_gpu_data['MEMORY_TOTAL']['TEXT']
-        if math.isnan(memory_used_mb):
-            memory_used_mb = 0
+        if math.isnan(total_memory_mb):
+            total_memory_mb = 0
             if gpu_mem_total_text_data['SHOW']:
                 logger.warning("Your GPU total memory capacity (M) is not supported yet")
                 gpu_mem_total_text_data['SHOW'] = False