Update RELEASE_NOTES.md for 1.5.41 release

[Arkatufus]

1.5.41 May 6th, 2025

Akka.NET v1.5.41 contains several bug fixes and also adds new quality of life features to Akka.TestKit and Akka.Streams.

• TestKit: Ensure that EventFilter respects WithinAsync timeout blocks
• TestKit: Add support to XUnit 3 to Akka.TestKit.Xunit
• TestKit: Improve ExpectNextNAsync() error message clarity
• Remoting: Mark IDaemonMsg with public interface marker
• Streams: Fix cancelled sinks are blocking other BroadcastHub consumers
• Streams: Allow GroupBy to use infinite output sub-streams
• Analyzers: Bump Akka.Analyzers from 0.3.1 to 0.3.2

XUnit V3 Support

We've added XUnit v3 support to Akka.TestKit.Xunit, please use this package if you're planning on using and/or migrating to the latest XUnit 3 platform.

Note that due to XUnit v3 limitation, please make sure that you're following these minimum requirements:

• Use net472 and above if you're targeting .NET Framework.
• Use net8.0 and above if you're targeting .NET Core.
• Reference the xunit.v3.* packages v2.0.2 and above.
• Reference the xunit.runner.visualstudio package v3.1.0 and above.

Akka.Streams GroupBy API improvement

Akka.Streams GroupBy stage can now, and now by default, create an unlimited number of sub-streams. Simply omit the maxSubstreams parameter or change the maxSubstreams parameter to a negative value to enable this feature.

Note

This can cause memory leak issue if you design your stream to be long-running, and it is designed to generate/process a very large number of sub-streams.

4 contributors since release 1.5.40

COMMITS	LOC+	LOC-	AUTHOR
9	1757	1690	Aaron Stannard
6	1089	542	Gregorius Soedharmo
1	3	16	Simon Cropp
1	10	2	JuYoung Kim

[Aaronontheweb]

LGTM