trigger build.rs rebuild on commit

build.rs

@@ -1 +1,8 @@
-fn main() -> shadow_rs::SdResult<()> { shadow_rs::new() }
+use std::process::Command;
+
+fn main() -> shadow_rs::SdResult<()> {
+    let output = Command::new("git").args(&["rev-parse", "HEAD"]).output().unwrap();
+    let git_hash = String::from_utf8(output.stdout).unwrap();
+    println!("cargo:rustc-env=GIT_HASH={}", git_hash);
+    shadow_rs::new()
+}