Use script_setup in blueprint_stocks example (rerun-io#5677)

### What
Script flags weren't working as expected.

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examples/python/blueprint_stocks/main.py

@@ -166,7 +166,7 @@ def main() -> None:
         else:
             blueprint = viewport
 
-    rr.init("rerun_example_blueprint_stocks", spawn=True, blueprint=blueprint)
+    rr.script_setup(args, "rerun_example_blueprint_stocks", blueprint=blueprint)
 
     # In a future blueprint release, this can move into the blueprint as well
     for symbol in symbols: