Allow negative integers as durations

[littldr]

Hi!

the Duration getter currently allows the passed value to be an positive integer or a parsable duration string.
So that if I pass an integer like 1 I get the same results as if I would pass 1ns.

But Golang allows us to have negative duration, e.g. time.ParseDuration("-1ns").
Passing the duration string -1ns works with konaf as expected, but if I pass -1 it will return me a duration with the length of zero.

We stumbled about this unexpected behavior in this issue: ory/hydra#2651 (comment)

For consistency reasons I would propose to allow negative integers and treat them in the same way as positive ones.

What do you think?

[knadh]

Yep, makes sense. Released v1.2.2 with this fix.