Fix changelog date woorelease missed

Author: allendav

readme.txt

@@ -38,7 +38,7 @@ If you get stuck, you can ask for help in the Plugin Forum.
 
 == Changelog ==
 
-= 1.4.15 - 2020-xx-xx =
+= 1.4.15 - 2020-03-30 =
  * Tweak - WC tested up to 4.0
  * Tweak - WP tested up to 5.4