Set Redis session expiry

[james-sheppard-gov-uk]

cache expiry set to 72000s (20h)?

do we need to tell the user the expiry?

[DavidBiddle]

Relevant WCAG bit:

Success Criterion 2.2.1 Timing Adjustable (Level A): For each time limit that is set by the content, at least one of the following is true:

Turn off

• The user is allowed to turn off the time limit before encountering it; or

Adjust

• The user is allowed to adjust the time limit before encountering it over a wide range that is at least ten times the length of the default setting; or

Extend

• The user is warned before time expires and given at least 20 seconds to extend the time limit with a simple action (for example, "press the space bar"), and the user is allowed to extend the time limit at least ten times; or

Real-time Exception

• The time limit is a required part of a real-time event (for example, an auction), and no alternative to the time limit is possible; or

Essential Exception

• The time limit is essential and extending it would invalidate the activity; or
  20 Hour Exception
• The time limit is longer than 20 hours.

Source: https://www.w3.org/WAI/WCAG21/Understanding/timing-adjustable