delete Python 2 (object) compat

Bug: 302871152
Change-Id: I39636d73a6e1d69efa8ade74f75c5381651e6dc8
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/390054
Commit-Queue: Mike Frysinger <vapier@google.com>
Reviewed-by: Aravind Vasudevan <aravindvasudev@google.com>
Tested-by: Mike Frysinger <vapier@google.com>
diff --git a/git_config.py b/git_config.py
index c19f766..4f053ed 100644
--- a/git_config.py
+++ b/git_config.py
@@ -70,7 +70,7 @@
     return ".".join(parts)
 
 
-class GitConfig(object):
+class GitConfig:
     _ForUser = None
 
     _ForSystem = None
@@ -430,7 +430,7 @@
         return os.path.join(repo_config_dir, ".repoconfig/config")
 
 
-class RefSpec(object):
+class RefSpec:
     """A Git refspec line, split into its components:
 
     forced:  True if the line starts with '+'
@@ -541,7 +541,7 @@
     yield cookiefile, None
 
 
-class Remote(object):
+class Remote:
     """Configuration options related to a remote."""
 
     def __init__(self, config, name):
@@ -723,7 +723,7 @@
         return self._config.GetString(key, all_keys=all_keys)
 
 
-class Branch(object):
+class Branch:
     """Configuration options related to a single branch."""
 
     def __init__(self, config, name):