dgram: fix linting issue

Not sure why CI (and `make -j8 test` at the time of landing) showed this
as being OK, but `make lint-js` is failing now.

PR-URL: https://github.com/nodejs/node/pull/22175


Reviewed-By: Gus Caplan <me@gus.host>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>