[css-backgrounds-3] Fix metadata

Author: fantasai

css-backgrounds-3/Overview.bs

@@ -1,8 +1,6 @@
 <pre class='metadata'>
 Title: CSS Backgrounds and Borders Module Level 3
-Status: CRD
-Date: 2021-07-26
-Deadline: 2021-08-22
+Status: ED
 Implementation Report: https://test.csswg.org/harness/results/css-backgrounds-3_dev/grouped/
 Work Status: Testing
 Shortname: css-backgrounds