Update lockbox-datastore dependency for "touch" method

[devinreams]

A "touch" method is coming to the datastore at mozilla-lockwise/lockbox-datastore#95 and mozilla-lockwise/lockbox-datastore#96 so we can know when an item was last used.

We can use this issue to prioritize any corresponding extension work including, but not limited to:

• updating the package / dependency
• incorporating the method itself
• updating any metrics or reporting needed
• regression testing