chore: Add changelog and bump version to 3.3.6-RC3

Author: tgodzik

changelogs/3.3.6-RC3.md

@@ -0,0 +1,16 @@
+# Backported fixes
+
+- classfile reader: handle JDK 9+ constant types in constant pool [#19533](https://github.com/scala/scala3/pull/19533)
+- Update asm to 9.8.0 [#23004](https://github.com/scala/scala3/pull/23004)
+
+# Contributors
+
+Thank you to all theq contributors who made this release possible 🎉
+
+According to `git shortlog -sn --no-merges 3.3.6-RC2..3.3.6-RC3` these are:
+
+```
+     2  Seth Tisue
+     1  Tomasz Godzik
+     1  philippus
+```

project/Build.scala

@@ -108,7 +108,7 @@ object Build {
    *  During release candidate cycle incremented by the release officer before publishing a subsequent RC version;
    *  During final, stable release is set exactly to `developedVersion`.
   */
-  val baseVersion = s"$developedVersion-RC2"
+  val baseVersion = s"$developedVersion-RC3"
 
   /** The version of TASTY that should be emitted, checked in runtime test
    *  For defails on how TASTY version should be set see related discussions: