Remove extra parentheses from tools/fmt.sh

Author: taiki-e

tools/fmt.sh

@@ -5,7 +5,8 @@
 # Usage:
 #    ./tools/fmt.sh
 #
-# This script is needed because `cargo fmt` cannot recognize modules defined inside macros.
+# This is similar to `cargo fmt`, but unlike `cargo fmt`, it can recognize
+# modules defined inside macros.
 # Refs: https://github.com/rust-lang/rustfmt/issues/4078
 
 set -euo pipefail
@@ -15,12 +16,13 @@ cd "$(cd "$(dirname "${0}")" && pwd)"/..
 
 # shellcheck disable=SC2046
 if [[ -z "${CI:-}" ]]; then
-    (
-        # `cargo fmt` cannot recognize modules defined inside macros so run rustfmt directly.
-        rustfmt $(git ls-files "*.rs")
-    )
+    # `cargo fmt` cannot recognize modules defined inside macros, so run
+    # rustfmt directly.
+    # Refs: https://github.com/rust-lang/rustfmt/issues/4078
+    rustfmt $(git ls-files "*.rs")
 else
-    (
-        rustfmt --check $(git ls-files "*.rs")
-    )
+    # `cargo fmt` cannot recognize modules defined inside macros, so run
+    # rustfmt directly.
+    # Refs: https://github.com/rust-lang/rustfmt/issues/4078
+    rustfmt --check $(git ls-files "*.rs")
 fi