fix(schema): correct namespaced field type from string to boolean

Update cumulusci.jsonschema.json to fix the data type for the 'namespaced'
field from string to boolean, which better reflects its intended usage.

Author: dipakparmar

cumulusci/schema/cumulusci.jsonschema.json

@@ -421,7 +421,7 @@
                 },
                 "namespaced": {
                     "title": "Namespaced",
-                    "type": "string"
+                    "type": "boolean"
                 },
                 "setup_flow": {
                     "title": "Setup Flow",