Update 01-quickstart.md

Change of version number to reflect the latest ESMValTool release.

Author: hb326

_episodes/01-quickstart.md

@@ -2,7 +2,7 @@
 title: "Quickstart guide"
 teaching: 2
 exercises: 8
-compatibility: ESMValTool v2.11.0
+compatibility: ESMValTool v2.12.0
 
 questions: