PostgreSQL parameter names are case-insensitive, but the denylist
check was case-sensitive, allowing bypass via mixed-case names
(e.g., ARCHIVE_COMMAND instead of archive_command).
Normalize parameter names to lowercase before checking against the
denylist to prevent security bypass.
Thanks to CodeRabbit for catching this security issue.
Signed-off-by: IvanHunters <xorokhotnikov@gmail.com>