Wrong enum conversion

[Yevgnen]

With the following definition,

class TaskType(str, enum.Enum):
    TASK_TYPE1 = 'task_type1'
    TASK_TYPE2 = 'task_type2'

the enum class instance is converted into a list. I would expect a string instead since str mixin is being inherited.

In [78]: json2html.json2html.convert({'task_type': TaskType.TASK_TYPE1})
'<table border="1"><tr><th>task_type</th><td><ul><li>t</li><li>a</li><li>s</li><li>k</li><li>_</li><li>t</li><li>y</li><li>p</li><li>e</li><li>1</li></ul></td></tr></table>'

Thanks!