kria.bucket: Simplify the (call) invocation

Keywords can act as functions that look themselves up in their
arguments, therefore #(:keys %) is the same as :keys alone, in a
function context. With this in mind, the (call) invocation in
kria.bucket can be simplified.

Noticed when running lein kibit.

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>
Merge pull request #5 from algernon/h/kibit

kria.bucket: Simplify the (call) invocation