Remove unnecessary allow_duplicate_keys.

Author: felixfontein

docs/docsite/reformat-yaml.py

@@ -12,7 +12,6 @@
 def main() -> None:
     yaml = YAML(typ='rt')
     yaml.indent(mapping=2, sequence=4, offset=2)
-    yaml.allow_duplicate_keys = True
 
     # Load
     data = yaml.load(sys.stdin)