Remove Python2-related __future__ imports

[vergeev]

Closes #1636

Removes every from __future__ import print_function outside of the vendor directory.

Also removes other Python2-related imports, such as:

• from __future__ import with_statement
• from __future__ import absolute_import

[linux-foundation-easycla[bot]]

The committers listed above are authorized under a signed CLA.

• :white_check_mark: login: vergeev / name: Pavel Vergeev (cd5dbff766ec7b7d4ab3e34030ce9eeaa0cf6548, 2048808627f6ffc21b777a23c361b76771d2f2ec)

[JeanChristopheMorinPerso]

Thank you @vergeev! I triggered builds to see if everything passes.

Can I ask you if you found this issue through https://clotributor.dev/search?foundation=aswf?

[vergeev]

Can I ask you if you found this issue through https://clotributor.dev/search?foundation=aswf?

I did find it through CLOTributor, yes :)