clean up an unused pair of parentheses
clean up an unused pair of parentheses

While this might seem like too trivial of a stylistic nitpick to deserve
its own commit, this is needed to unblock rust-lang/rust#46980 (which makes
the unused-parens lint look at function arguments).

tsurai/cargo,rust-lang/cargo,eminence/cargo,vojtechkral/cargo,eminence/cargo,tsurai/cargo,rustyhorde/cargo,tsurai/cargo,vojtechkral/cargo,nipunn1313/cargo,vojtechkral/cargo,rustyhorde/cargo,rust-lang/cargo,tsurai/cargo,tshepang/cargo,nipunn1313/cargo,rustyhorde/cargo,tshepang/cargo,tshepang/cargo,nipunn1313/cargo,tshepang/cargo,eminence/cargo,vojtechkral/cargo,nipunn1313/cargo,rust-lang/cargo,eminence/cargo,rust-lang/cargo,rustyhorde/cargo,tsurai/cargo