modify backend check logic

run.bat

@@ -1,4 +1,5 @@
 @echo off
 set PYTHONIOENCODING=utf-8
 set AUTOGGUF_LANGUAGE=en-US
+set AUTOGGUF_CHECK_BACKEND=disabled
 python src/main.py

src/AutoGGUF.py

@@ -89,6 +89,7 @@ def __init__(self):
         right_layout.addWidget(download_group)
 
         # Initialize releases and backends
+        if os.environ.get('AUTOGGUF_CHECK_BACKEND', '').lower() == 'enabled':
             self.refresh_releases()
         self.refresh_backends()