Add support for DesiredCount

[romankydybets]

Hi Team,
it would be great to have DesiredCount support during deployment.
https://docs.aws.amazon.com/cli/latest/reference/ecs/update-service.html
--desired-count

[mendhak]

Looks like it's been merged, but not released yet?

#505

[romankydybets]

I completely lost, how to perform release?

[amazreech]

Closed with PR 505 as part of release v1.5.0