Admin interface: Add buttons to delete users / groups / participations

1 job for admin-delete-stuff in 1 minute and 28 seconds (queued for 1 second)
Status Job ID Name Coverage
  Test
failed #2099
test

00:01:28

 
Name Stage Failure
failed
test Test
error: could not compile `medal`.

To learn more, run the command again with --verbose.
warning: build failed, waiting for other jobs to finish...
error: aborting due to 2 previous errors; 1 warning emitted

error: build failed
make: *** [Makefile:23: clippy] Error 101
ERROR: Job failed: exit code 1