style: format code with Rustfmt

This commit fixes the style issues introduced in 786f124 according to the output
from Rustfmt.

Details: None

Author: deepsource-autofix[bot]

build.rs

@@ -47,4 +47,4 @@ fn main() {
     // 当 git 变化时重新构建
     println!("cargo:rerun-if-changed=.git/HEAD");
     println!("cargo:rerun-if-changed=.git/index");
-}
+}