Update the version in bakefile presets to 3.0 too.

Also mention this file in the list of files to update when changing the
version.

Closes #15577.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@74992 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775