use push() instead of push_str() for single char (#394)

This solves a clippy warning

1 files changed, 2 insertions, 2 deletions

diff --git a/src/features/side_by_side.rs b/src/features/side_by_side.rs
index 358261b8..a9abfb03 100644
--- a/src/features/side_by_side.rs
+++ b/src/features/side_by_side.rs
@@ -107,7 +107,7 @@ pub fn paint_minus_and_plus_lines_side_by_side<'a>(
             background_color_extends_to_terminal_width,
             config,
         ));
-        output_buffer.push_str("\n");
+        output_buffer.push('\n');
     }
 }
 
@@ -171,7 +171,7 @@ pub fn paint_zero_lines_side_by_side(
             config,
         );
         output_buffer.push_str(&right_panel_line);
-        output_buffer.push_str("\n");
+        output_buffer.push('\n');
     }
 }