Add changelog for 3.1.3-RC4

Author: Kordyjan

changelogs/3.1.3-RC4.md

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+# Notable changes
+
+- Fix lack of type avoidance in argument lifting [#15229](https://github.com/lampepfl/dotty/pull/15229)
+- Avoid overeager completion of Java annotations in classfile parser [#15185](https://github.com/lampepfl/dotty/pull/15185)
+- Implement scalac script in Scala [#15212](https://github.com/lampepfl/dotty/pull/15212)
+
+# Contributors
+
+Thank you to all the contributors who made this release possible 🎉
+
+According to `git shortlog -sn --no-merges 3.1.3-RC3..3.1.3-RC4` these are:
+
+```
+2  Paweł Marks
+1  Guillaume Martres
+1  Jamie Thompson
+1  Tom Grigg
+```