Removed Python legacy __future__ imports (#8697)

There are still some left, but the `modification_check` test fails. Some are still in `tools`, and they can probably be removed as well. `with_statement` was introduced officially in Python 2.5, so there's really old stuff in the code base.

certbot-ci/certbot_integration_tests/assets/hook.py

@@ -1,5 +1,4 @@
 #!/usr/bin/env python
-from __future__ import print_function
 import os
 import sys
 

certbot-ci/certbot_integration_tests/certbot_tests/test_main.py

@@ -1,5 +1,4 @@
 """Module executing integration tests against certbot core."""
-from __future__ import print_function
 
 import os
 from os.path import exists

certbot-ci/certbot_integration_tests/conftest.py

@@ -6,7 +6,6 @@ for a directory a specific configuration using built-in pytest hooks.
 
 See https://docs.pytest.org/en/latest/reference.html#hook-reference
 """
-from __future__ import print_function
 import contextlib
 import subprocess
 import sys

certbot-ci/certbot_integration_tests/utils/acme_server.py

@@ -1,6 +1,5 @@
 #!/usr/bin/env python
 """Module to setup an ACME CA server environment able to run multiple tests in parallel"""
-from __future__ import print_function
 
 import argparse
 import errno

certbot-ci/certbot_integration_tests/utils/certbot_call.py

@@ -1,6 +1,5 @@
 #!/usr/bin/env python
 """Module to call certbot in test mode"""
-from __future__ import absolute_import
 
 import os
 import subprocess

certbot-ci/certbot_integration_tests/utils/dns_server.py

@@ -1,7 +1,5 @@
 #!/usr/bin/env python
 """Module to setup an RFC2136-capable DNS server"""
-from __future__ import print_function
-
 import os
 import os.path
 import shutil

certbot-ci/certbot_integration_tests/utils/misc.py

@@ -311,7 +311,7 @@ def echo(keyword, path=None):
     if not re.match(r'^\w+$', keyword):
         raise ValueError('Error, keyword `{0}` is not a single keyword.'
                          .format(keyword))
-    return '{0} -c "from __future__ import print_function; print(\'{1}\')"{2}'.format(
+    return '{0} -c "print(\'{1}\')"{2}'.format(
         os.path.basename(sys.executable), keyword, ' >> "{0}"'.format(path) if path else '')
 
 

certbot-ci/windows_installer_integration_tests/conftest.py

@@ -6,7 +6,7 @@ for a directory a specific configuration using built-in pytest hooks.
 
 See https://docs.pytest.org/en/latest/reference.html#hook-reference
 """
-from __future__ import print_function
+
 import os
 
 ROOT_PATH = os.path.dirname(os.path.dirname(os.path.dirname(__file__)))