Fix release notes (#6)

The number in the filename is the PR, and the contents of the file is a short description of the change (does not necessarily have to be exactly the same as the PR title).

Co-authored-by: Callum Dickinson <callum.dickinson@catalystcloud.nz>

Author: Callum027

changelog.d/4.removed.md

@@ -0,0 +1 @@
+Remove support for Python 3.8 and 3.9