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>

subcmds/branches.py

@@ -28,7 +28,7 @@ class BranchColoring(Coloring):
         self.notinproject = self.printer("notinproject", fg="red")
 
 
-class BranchInfo(object):
+class BranchInfo:
     def __init__(self, name):
         self.name = name
         self.current = 0

subcmds/sync.py

@@ -1908,7 +1908,7 @@ def _PostRepoFetch(rp, repo_verify=True, verbose=False):
             print("repo version %s is current" % rp.work_git.describe(HEAD))
 
 
-class _FetchTimes(object):
+class _FetchTimes:
     _ALPHA = 0.5
 
     def __init__(self, manifest):
@@ -1951,7 +1951,7 @@ class _FetchTimes(object):
             platform_utils.remove(self._path, missing_ok=True)
 
 
-class LocalSyncState(object):
+class LocalSyncState:
     _LAST_FETCH = "last_fetch"
     _LAST_CHECKOUT = "last_checkout"