truncate: remove read permissions from OpenOptions

Remove "read" permissions from the `OpenOptions` when opening a new file
just to truncate it. We will never read from the file, only write to
it. (Specifically, we will only call `File::set_len()`.)

src/uu/truncate/src/truncate.rs

@@ -189,12 +189,7 @@ fn truncate(
     };
     for filename in &filenames {
         let path = Path::new(filename);
-        match OpenOptions::new()
+        match OpenOptions::new().write(true).create(!no_create).open(path) {
-            .read(true)
-            .write(true)
-            .create(!no_create)
-            .open(path)
-        {
             Ok(file) => {
                 let fsize = match reference {
                     Some(_) => refsize,