werkzeug 1.0.0 removed symbols

[stephanwlee]

https://pypi.org/project/Werkzeug/1.0.0/ was release 2020-02-06 and it breaks our tests.

There are about 5 instances where we use werkzeug.BaseResponse (all in tests) but the API is now deprecated (werkzeug.wrappers.BaseResponse may be what we want).

Do note that this should impact CI, too, very soon (

tensorboard/tensorboard/pip_package/requirements.txt

Line 30 in 38a326b

werkzeug >= 0.11.15

)

[wchargin]

werkzeug >= 0.11.15 

At some point we should probably go through and constrain these by major
version boundaries…