Justify header when there are decorations but no grid

src/printer.rs

@@ -90,6 +90,8 @@ impl<'a> Printer<'a> {
                     .grid
                     .paint(if self.panel_width > 0 { "│" } else { "" }),
             )?;
+        } else {
+            write!(self.handle, "{}", " ".repeat(self.panel_width))?;
         }
 
         writeln!(

tests/snapshots/output/changes,header,numbers.snapshot.txt

@@ -1,4 +1,4 @@
-File: sample.rs
+       File: sample.rs
    1   struct Rectangle {
    2       width: u32,
    3       height: u32,

tests/snapshots/output/changes,header.snapshot.txt

@@ -1,4 +1,4 @@
-File: sample.rs
+  File: sample.rs
   struct Rectangle {
       width: u32,
       height: u32,

tests/snapshots/output/header,numbers.snapshot.txt

@@ -1,4 +1,4 @@
-File: sample.rs
+     File: sample.rs
    1 struct Rectangle {
    2     width: u32,
    3     height: u32,