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### _Why are the changes needed?_
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Bump sphinx to latest version. close#612
### _How was this patch tested?_
- [ ] Add some test cases that check the changes thoroughly including negative and positive cases if possible
- [ ] Add screenshots for manual tests if appropriate
- [ ] [Run test](https://kyuubi.readthedocs.io/en/latest/tools/testing.html#running-tests) locally before make a pull request
Closes#614 from pan3793/doc.
Closes#614
b1b2738 [Cheng Pan] [BUILD][DOCS] Bump sphinx
Authored-by: Cheng Pan <379377944@qq.com>
Signed-off-by: Kent Yao <yao@apache.org>
f742686357