Added missing closing paren which caused error

PHP Parse error:  syntax error, unexpected '->' (T_OBJECT_OPERATOR) in [project]/src/Application/Sonata/UserBundle/Admin/Entity/UserAdmin.php on line 85
Merge pull request #5 from TobiasWooldridge/master

Adding missing closing paren - (@jmather - and that's what I get for being snarky and not linting, hahah. Thank you @TobiasWooldridge)