Main: Fix launch if EXPORT_OPENAPI is unset

A default needs to be provided with getenv. Fix that with an empty
string.

Signed-off-by: kingbri <bdashore3@proton.me>

common/model.py

@@ -13,7 +13,7 @@ from common import config
 from common.logger import get_loading_progress_bar
 from common.utils import unwrap
 
-if not os.getenv("EXPORT_OPENAPI"):
+if not os.getenv("EXPORT_OPENAPI", "").lower() in ("true", "1"):
     from backends.exllamav2.model import ExllamaV2Container
 
     # Global model container