* Fix use of user_data field with spot_price in ec2 module (#37628)
The user_data field is base64 encoded inside of the boto library. In
Python3, base64 must be used with byte strings. So we make sure to
encode the user_data into a byte string before passing it on to the boto
library.
Fixes#34978
(cherry picked from commit 0d55081ba8)
* Python3 ec2 fix added to changelog
