fix: Fix call list datasources api returns error

[chaplinthink]

Closes #1788

Description

API endpoint returns incorrect data type, it should be List type.

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[Aries-ckt]

@chaplinthink , thanks for your contribution, could you add the page result for /datasources api?

[chaplinthink]

@chaplinthink , thanks for your contribution, could you add the page result for /datasources api?

@Aries-ckt I used datasources client api, reference: http://docs.dbgpt.cn/docs/api/datasource#list-datasource