fix(terminal): resize() now resizes fixed viewports (#1353)

`Terminal::resize()` on a fixed viewport used to do nothing due to
an accidentally shadowed variable. This now works as intended.

src/terminal/terminal.rs

@@ -219,7 +219,7 @@ where
                 )?
                 .0
             }
-            Viewport::Fixed(area) => area,
+            Viewport::Fixed(_) => area,
         };
         self.set_viewport_area(next_area);
         self.clear()?;