Fix grammar

Author: DJP

src/components/REPL.tsx

@@ -41,7 +41,7 @@ const REPL: React.VFC<ColumnDefinition<any>> = props => {
             {deprecated ? (
                 <div className="bg-yellow-100 border-l-4 border-yellow-500 text-yellow-700 p-4 mb-4" role="alert">
                     <p className="font-bold">Deprecated Column</p>
-                    <p className="my-2">This column has been deprecated. The feature will continue to work in apps that are currently using it, but new uses of the column is not supported. New apps are also unable to add this column.</p>
+                    <p className="my-2">This column has been deprecated. The feature will continue to work in apps that are currently using it, but new uses of the column are not supported. New apps are also unable to add this column.</p>
                 </div>
             ) : null}
             <div className="space-y-6">