pyupgrade: drop redundant `open()` modes On one hand, this gets rid of some py2 cruft (like `U` and `t` modes). OTOH, I like being explict. But there's no way to disable individual transformations (and this change is part of `_fix_tokens()`, which is even harder to selectively use locally), and I'd rather have less noise when using `pyupgrade`. Warning: `contrib/synthrepo.py` appears not to have been updated to py3, as it's passing str to `error.Abort`. But since it was opening the file in unicode on py2, this change is a no-op.

--- a/contrib/automation/hgautomation/aws.py	Mon Jan 06 01:44:46 2025 -0500
+++ b/contrib/automation/hgautomation/aws.py	Tue Jan 07 17:28:46 2025 -0500
@@ -332,7 +332,7 @@
         pub_full = key_path / f
         priv_full = key_path / ('keypair-%s' % name)
 
-        with open(pub_full, 'r', encoding='ascii') as fh:
+        with open(pub_full, encoding='ascii') as fh:
             data = fh.read()
 
         if not data.startswith('ssh-rsa '):