Update presubmit.py

Author: hunsche

infra/presubmit.py

@@ -86,7 +86,6 @@ class ProjectYamlChecker:
   VALID_SECTION_NAMES = [
       'architectures',
       'auto_ccs',
-      'base_os_version',
       'blackbox',
       'builds_per_day',
       'coverage_extra_args',