lint: fix a few Clippy errors

PR #3151

crates/printer/src/json.rs

@@ -571,7 +571,7 @@ impl<W: io::Write> JSON<W> {
         } else {
             json::to_writer(&mut self.wtr, message)?;
         }
-        self.wtr.write(&[b'\n'])?;
+        let _ = self.wtr.write(b"\n")?; // This will always be Ok(1) when successful.
         Ok(())
     }
 }

crates/printer/src/jsont.rs

@@ -190,7 +190,7 @@ impl<'a> Data<'a> {
     }
 
     #[cfg(not(unix))]
-    fn from_path(path: &Path) -> Data {
+    fn from_path(path: &Path) -> Data<'_> {
         // Using lossy conversion means some paths won't round trip precisely,
         // but it's not clear what we should actually do. Serde rejects
         // non-UTF-8 paths, and OsStr's are serialized as a sequence of UTF-16