Bump Akka to 2.6.20

Bump Akka to 2.6.20

https://akka.io/blog/news/2022/09/06/akka-2.6.20-released
https://github.com/real-logic/agrona/releases/tag/1.15.0
https://github.com/real-logic/agrona/releases/tag/1.15.1
https://github.com/real-logic/agrona/releases/tag/1.15.2
https://github.com/real-logic/aeron/releases/tag/1.38.0
https://github.com/real-logic/aeron/releases/tag/1.38.1

JIRA: CONTROLLER-2048
Change-Id: I4d3b2da9bd1a716403bfae5b957c73b05406ba15
Signed-off-by: Robert Varga <robert.varga@pantheon.tech>
(cherry picked from commit 2f5d6ed35dcae3c1ea40f89265410751c107e631)
(cherry picked from commit 16d97d4333ff5164adf3249a25c1991787512984)