Add a missing require.

This makes the rack_logger_test.rb runnable by itself (outside of the `rake test` suite).
"Naked" rescue clauses only catch StandardError subclasses.

Similar to #11497.
Merge pull request #11780 from thedarkone/logger-naked-rescue-fix

Rack::Logger naked rescue fix
test to express that we can't turn non-array columns to array columns.

Closes #11062