ssh provider limits to an old version of sshtunnel

[kurtqq]

ssh provider has limit to sshtunnel < 0.2

airflow/setup.py

Line 451 in 9d6ae60

'sshtunnel>=0.1.4,<0.2',

I don't know why? sshtunnel already released 0.4
I didn't open PR because I don't know this provider i just tried to install it and couldn't due to conflicts with other requirements in my system so eventually i used vitrual env to solve my problem but logging this issue so that someone who knows this code can handle it.

[potiuk]

Please simply just make a PR with it. We have automated suite of tests, if they pass, this means we should approve it.

[potiuk]

Same as #16698