chore: Make code compiles on JDK 23

[He-Pin]

Motivation:
Make code compiles on JDK 23
refs: #1725

Modification:
Add @nowarn("cat=deprecation")

Result:
Tested locally, it compiles now

[pjfanning]

I got this in the java 23 with scala 3 build

[01-17 20:08:03.894] [info] compiling 1 Scala source to /home/runner/work/pekko/pekko/actor/target/scala-3.3.4/CompileJdk9-classes ...
[01-17 20:08:03.905] [error] 23 is not a valid choice for -java-output-version
[01-17 20:08:03.906] [info]   scalac -help  gives more information
[01-17 20:08:03.906] [error] one error found

https://github.com/apache/pekko/actions/runs/12836052025/job/35796857450

[He-Pin]

@pjfanning Maybe we need to wait for the Scala 3.3.5?

[pjfanning]

lgtm - I think there is more to solve but this is a good start

[He-Pin]

@WojciechMazur I tested it with 3.3.5-RC1, but still later get:

[error] 23 is not a valid choice for -java-output-version
[info]   scalac -help  gives more information

[WojciechMazur]

@He-Pin Thank you for spotting this bug! The JDK 23 support was backported to 3.3.5-RC1, by mistake 1 single change that is no longer needed in Next was not applied in the LTS backport. We're release 3.3.5-RC3 with a fix on Monday

[He-Pin]

Is the 3.3.5-RC2 on the way, so next is 3.3.5-RC3? @WojciechMazur

[WojciechMazur]

Correct, it was going to be announced on Monday, becouse we're waiting for tooling confirmation