Bugfix accept additional attributes to the delete cookie

Recent browser changes mean that cookies will not be set if they have
the wrong combination of attributes e.g. SameSite none and not
secure. This also affects deletion which itself is a set cookie
command.

Only the SameSite and secure attributes are required, however it seems
more useful to accept all the possibilities for other edge cases.

See also https://chromestatus.com/feature/5633521622188032
4 jobs for master in 2 minutes and 52 seconds (queued for 1 second)
Status Job ID Name Coverage
  Test
passed #638631368
pages

00:01:33

passed #638631365
py37

00:01:23

passed #638631366
py38

00:02:52

 
  Deploy
passed pages:deploy

00:00:06