Add a newline to the generated JSON files

This adds a newline at the end of all cached ./.sqlx/... JSON files so that anyone who has "auto-newline" enabled in their IDE would not accidentally add it to the cached file. This also ensures that GitHub diff would not show an alarming red icon next to the end of the checked in sqlx files.

sqlx-macros-core/src/query/data.rs

@@ -1,6 +1,7 @@
 use std::collections::HashMap;
 use std::fmt::{Debug, Display, Formatter};
 use std::fs;
+use std::io::Write as _;
 use std::marker::PhantomData;
 use std::path::{Path, PathBuf};
 use std::sync::Mutex;
@@ -161,8 +162,15 @@ where
         // with persisting the file across filesystems.
         let mut tmp_file = tempfile::NamedTempFile::new_in(tmp_dir)
             .map_err(|err| format!("failed to create query file: {:?}", err))?;
+
         serde_json::to_writer_pretty(tmp_file.as_file_mut(), self)
             .map_err(|err| format!("failed to serialize query data to file: {:?}", err))?;
+        // Ensure there is a newline at the end of the JSON file to avoid accidental modification by IDE
+        // and make github diff tool happier
+        tmp_file
+            .as_file_mut()
+            .write_all(b"\n")
+            .map_err(|err| format!("failed to append a newline to file: {:?}", err))?;
 
         tmp_file
             .persist(dir.as_ref().join(format!("query-{}.json", self.hash)))