fix: Fix variable assign num not working

--bug=1052497 --user=刘瑞斌 【变量赋值】-将全局变量赋值为num类型，输出时报错 https://www.tapd.cn/57709429/s/1659733

Author: liuruibin

apps/application/flow/step_node/variable_assign_node/impl/base_variable_assign_node.py

@@ -30,11 +30,15 @@ def execute(self, variable_list, stream, **kwargs) -> NodeResult:
                             val = json.loads(variable['value'])
                         self.workflow_manage.context[variable['fields'][1]] = val
                         result['output_value'] = variable['value'] = val
-                    else:
+                    elif variable['type'] == 'string':
                         # 变量解析 例如：{{global.xxx}}
                         val = self.workflow_manage.generate_prompt(variable['value'])
                         self.workflow_manage.context[variable['fields'][1]] = val
                         result['output_value'] = val
+                    else:
+                        val = variable['value']
+                        self.workflow_manage.context[variable['fields'][1]] = val
+                        result['output_value'] = val
                 else:
                     reference = self.get_reference_content(variable['reference'])
                     self.workflow_manage.context[variable['fields'][1]] = reference