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, 1 insertions, 1 deletions

diff --git a/mesonbuild/modules/fs.py b/mesonbuild/modules/fs.py
index 7de8cf7..fd1e99b 100644
--- a/mesonbuild/modules/fs.py
+++ b/mesonbuild/modules/fs.py
@@ -211,7 +211,7 @@ class FSModule(ExtensionModule):
         if path_is_in_root(Path(path), Path(build_dir), resolve=True):
             raise MesonException('path must not be in the build tree')
         try:
-            with open(path, 'r', encoding=encoding) as f:
+            with open(path, encoding=encoding) as f:
                 data = f.read()
         except UnicodeDecodeError:
             raise MesonException(f'decoding failed for {path}')