📝 Add a change note for PR jazzband#2257

Author: webknjaz

changelog.d/2257.packaging.md

@@ -0,0 +1,10 @@
+The core packaging metadata started exposing a new `supported` extra
+-- by {user}`beruic`, {user}`sirosen` and {user}`webknjaz`.
+
+This new opt-in install-level feature limits the `pip` dependency to
+the latest version we're testing in our CI at the time of release.
+
+<!-- pyml disable-num-lines 2 commands-show-output -->
+```console
+$ pip install 'pip-tools [supported]'
+```