VERSION file should be 12.0, not 11.12

This was apparently causing Gitlab.version_info to return the wrong values, causing the wrong images to be loaded via CI_SERVER_VERSION.

VERSION file should be 12.0, not 11.12
3796a49c · Stan Hu · 88a12332 · 3796a49c
Commit 3796a49c authored 5 years ago by Stan Hu
--- a/VERSION
+++ b/VERSION
-11.12.0-pre
+12.0.0-pre