[EN] Fix support for "plural of" template

[BoboTiG]

• Wiktionary page: https://en.wiktionary.org/wiki/vertuus

Wikicode:

{{plural of|en|nodot=y|vertuu}}

Output:

nodot=y

Expected:

vertuu

[BoboTiG]

Fixed on the Wiktionary as it was the only occurrence.