capybara_accessible_selectors 0.16 resolves role selectors such as
`:columnheader` by the computed accessible name. In a browser that name
folds in the CSS `text-transform: uppercase` styling and the column
action-menu trigger text, so `have_columnheader("Subject")` no longer
matches a header whose accessible name resolves to "SUBJECT Open menu".
Sets an explicit `aria-label` equal to the plain caption on each header
cell, in both the server-rendered tables and the work package table, so
the accessible name is the column title alone. This also improves screen
reader output, which previously announced the uppercased text and the
menu label.
Alexander Brandon Coles
0b4bcb5d3c