Fix clippy complaint in iron_sessionstorage copy

1 job for admin-delete-stuff in 5 minutes and 43 seconds (queued for 1 second)
Status Job ID Name Coverage
  Test
failed #2107
test

00:05:43

 
Name Stage Failure
failed
test Test
error: aborting due to previous error

error: could not compile `iron-sessionstorage`.

To learn more, run the command again with --verbose.
warning: build failed, waiting for other jobs to finish...
error: build failed
make: *** [Makefile:23: clippy] Error 101
ERROR: Job failed: exit code 1