[chrome-gnome-shell] readme: drop Shell version since all Shell versions are supported.

[Yuri Konotopov <ykonotopov src gnome org>]

commit c6299d782b1abdd52c121413161174d7feba9e5e
Author: Yuri Konotopov <ykonotopov gnome org>
Date:   Mon Jan 7 17:38:37 2019 +0400

    readme: drop Shell version since all Shell versions are supported.

 README.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/README.md b/README.md
index 7afc3e8..b5dab12 100644
--- a/README.md
+++ b/README.md
@@ -11,7 +11,7 @@ that provides integration with GNOME Shell and the corresponding extensions repo
 
 Requirements
 ------------
- * GNOME Shell up to 3.28
+ * GNOME Shell
  * Python 2.7+ or 3.x
  * PyGObject
  * Python Requests 2.x