Simplify warning

Author: stefanradev93

bayesflow/__init__.py

@@ -40,9 +40,9 @@ def setup():
         torch.autograd.set_grad_enabled(False)
 
         logging.warning(
-            "When using torch backend, we need to disable autograd by default to avoid excessive memory usage. Use\n"
-            "with torch.enable_grad():\n"
-            "in contexts where you need gradients (e.g. custom training loops)."
+            "Autograd is disabled by default to avoid excessive memory usage. "
+            "If you need gradients (e.g., custom training loops), use\n"
+            "with torch.enable_grad():"
         )