Use upstream in tools/maint/create_release.py. NFC

Author: sbc100

tools/maint/create_release.py

@@ -59,15 +59,15 @@ def main():
   branch_name = 'version_' + release_version
 
   # Create a new git branch
-  subprocess.check_call(['git', 'checkout', '-b', branch_name, 'origin/main'], cwd=root_dir)
+  subprocess.check_call(['git', 'checkout', '-b', branch_name, 'upstream/main'], cwd=root_dir)
 
   # Create auto-generated changes to the new git branch
   subprocess.check_call(['git', 'add', '-u', '.'], cwd=root_dir)
   subprocess.check_call(['git', 'commit', '-m', f'Mark {release_version} as released'], cwd=root_dir)
   print('New release created in branch: `%s`' % branch_name)
 
-  # Push new branch to origin
-  subprocess.check_call(['git', 'push', 'origin', branch_name], cwd=root_dir)
+  # Push new branch to upstream
+  subprocess.check_call(['git', 'push', 'upstream', branch_name], cwd=root_dir)
 
   # TODO(sbc): Maybe create the tag too
   return 0