Fix `to_json` method for charts (#68) #202

Job	Run time
Is release?	14s
Repository changes	4s
Charts tests	0s
Charts release	0s
Build Docker Image	0s
Build E2B template	0s
JS Tests	0s
Python Tests / Build and test SDK	1m 21s
Release	51s
Code Interpreter Release Failed - Slack Notification	0s
	2m 30s

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