fix progress declaration (#1628)

Co-authored-by: Fred Lefévère-Laoide <Fred.Lefevere-Laoide@Taipy.io>

taipy/gui/viselements.json

@@ -1264,7 +1264,7 @@
                         "name": "value",
                         "type": "dynamic(int)",
                         "doc": "If set, then the value represents the progress percentage that is shown.TODO - if unset?",
-                        "default_property": "true"
+                        "default_property": true
                     },
                     {
                         "name": "linear",
@@ -1281,8 +1281,8 @@
                     {
                         "name": "render",
                         "type": "dynamic(bool)",
-                        "doc": "If False, this progress indicator is hidden from the page.",
-                        "default_property": "true"
+                        "default_value": "True",
+                        "doc": "If False, this progress indicator is hidden from the page."
                     }
                 ]
             }