Prepare Release using 'release-plan'

Author: ef4

release-plan-stderr.txt

@@ -0,0 +1,7 @@
+# Unlabeled Changes
+
+* `@ember/string`
+  * [#444](https://github.com/emberjs/ember-string/pull/444) Manually tell CI to use pnpm 9 everywhere ([@NullVoxPopuli](https://github.com/NullVoxPopuli))
+
+
+*Cannot plan release until the above changes are labeled*.