Add Git commit hash to version string

Fixes #1348

build.rs

@@ -0,0 +1,19 @@
+use std::process::Command;
+
+fn main() {
+    let mut version = String::from(env!("CARGO_PKG_VERSION"));
+    if let Some(commit_hash) = commit_hash() {
+        version = format!("{version} ({commit_hash})");
+    }
+    println!("cargo:rustc-env=VERSION={version}");
+}
+
+fn commit_hash() -> Option<String> {
+    Command::new("git")
+        .args(["rev-parse", "--short", "HEAD"])
+        .output()
+        .ok()
+        .filter(|output| output.status.success())
+        .and_then(|output| String::from_utf8(output.stdout).ok())
+        .map(|hash| hash.trim().into())
+}