bump web
bump web

concourse/concourse#2000

Submodule src/github.com/concourse/web 2ba4258b..b8e29c3e:
  > fix html title tag on one off build

Signed-off-by: Rui Yang <10d6ef426b5f71d33c3d9e2459db4a0e3700cdde@pivotal.io>

concourse/concourse,concourse/concourse,concourse/concourse,concourse/concourse,concourse/concourse