various python neatness cleanups

All changes were created by running

"pyupgrade --py3-only --keep-percent-format"

and committing the results. I have not touched string formatting for
now.

- use set literals
- simplify .format() parameter naming
- remove __future__
- remove default "r" mode for open()
- use OSError rather than compatibility aliases
- remove stray parentheses in function(generator) scopes

1 files changed, 0 insertions, 1 deletions

diff --git a/skip_ci.py b/skip_ci.py
index 5e0a7aa..4ee4466 100755
--- a/skip_ci.py
+++ b/skip_ci.py
@@ -13,7 +13,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from __future__ import print_function
 
 import argparse
 import os