fix recompiling every time in uv-python (#16214)

Cargo is currently recompiling uv-python on every invocation because the
minified JSON output file is getting a mod time newer than the last run.
Instead, set the mod time of the output file to the same as the input
file.

Author: dead10ck

crates/uv-python/build.rs

@@ -1,3 +1,6 @@
+#[allow(clippy::disallowed_types)]
+use std::fs::{File, FileTimes};
+use std::io::Write;
 use std::path::PathBuf;
 use std::{env, fs};
 
@@ -36,16 +39,37 @@ fn main() {
 
     let json_data: serde_json::Value = serde_json::from_str(
         #[allow(clippy::disallowed_methods)]
-        &fs::read_to_string(version_metadata).expect("Failed to read download-metadata.json"),
+        &fs::read_to_string(&version_metadata).expect("Failed to read download-metadata.json"),
     )
     .expect("Failed to parse JSON");
 
     let filtered_data = process_json(&json_data);
 
+    #[allow(clippy::disallowed_types)]
+    let mut out_file = File::create(version_metadata_minified)
+        .expect("failed to open download-metadata-minified.json");
+
     #[allow(clippy::disallowed_methods)]
-    fs::write(
-        version_metadata_minified,
-        serde_json::to_string(&filtered_data).expect("Failed to serialize JSON"),
-    )
-    .expect("Failed to write minified JSON");
+    out_file
+        .write_all(
+            serde_json::to_string(&filtered_data)
+                .expect("Failed to serialize JSON")
+                .as_bytes(),
+        )
+        .expect("Failed to write minified JSON");
+
+    // Cargo uses the modified times of the paths specified in
+    // `rerun-if-changed`, so fetch the current file times and set them the same
+    // on the output file.
+    #[allow(clippy::disallowed_methods)]
+    let meta =
+        fs::metadata(version_metadata).expect("failed to read metadata for download-metadata.json");
+
+    out_file
+        .set_times(
+            FileTimes::new()
+                .set_accessed(meta.accessed().unwrap())
+                .set_modified(meta.modified().unwrap()),
+        )
+        .expect("failed to write file times to download-metadata-minified.json");
 }