Update RELEASE_NOTES.md for 1.5.25 (#83)

Author: Arkatufus

RELEASE_NOTES.md

@@ -1,3 +1,8 @@
+## [1.5.25] / 24 June 2024
+* [Update Akka.NET to 1.5.25](https://github.com/akkadotnet/akka.net/releases/tag/1.5.25)
+* [Update Akka.Hosting to 1.5.25](https://github.com/akkadotnet/Akka.Hosting/releases/tag/1.5.25)
+* [Downgrade target platform to .NET Standard 2.0](https://github.com/akkadotnet/Akka.Serialization.Compressed/pull/80)
+
 ## [1.5.8] / 27 June 2023
 * [Update Akka.NET to 1.5.8](https://github.com/akkadotnet/akka.net/releases/tag/1.5.8)
 * [Update Akka.Hosting to 1.5.8](https://github.com/akkadotnet/Akka.Hosting/releases/tag/1.5.8)