fix(osr): correct double colon in the example start URL (#473)

The osr example's start URL was "https:://github.com", which is not a valid URL, so
the example loaded an error page instead of github.com.

Beyond showing the wrong page this makes the example misleading as an off-screen
rendering reference: an error page is nearly static, so it produces very few
OnAcceleratedPaint callbacks, and a healthy shared-texture path can look broken.

Closes #472

examples/osr/src/main.rs

@@ -297,7 +297,7 @@ impl ApplicationHandler for App {
         let browser = cef::browser_host_create_browser_sync(
             Some(&window_info),
             Some(&mut ClientBuilder::build(render_handler)),
-            Some(&"https:://github.com".into()),
+            Some(&"https://github.com".into()),
             Some(&browser_settings),
             None,
             context.as_mut(),