Make celery import conditional in __init__.py

simulationserver/__init__.py

@@ -1,3 +1,9 @@
-from .celery import app as celery_app
+import os
 
-__all__ = ('celery_app',)
+HF_SPACES = os.environ.get('HF_SPACES', '').lower() in ('true', '1', 'yes')
+
+if not HF_SPACES:
+    from .celery import app as celery_app
+    __all__ = ('celery_app',)
+else:
+    __all__ = ()