add announcement for upcoming closure of NumPy 2.0 migration

Author: h-vetinari

news/2025-05-20-numpy-2-migration-closure.md

@@ -0,0 +1,12 @@
+# Upcoming closure of NumPy 2.0 migration
+
+NumPy 2.0 was a big change (the first major version in 15 years). For more than a year, we
+have been migrating feedstocks from NumPy 1.x to NumPy 2.x, and while not every affected
+feedstock has been done, we are planning to conclude the migration at the end of May.
+
+For feedstocks that are not compatible with v2.x yet, this means you will have to add
+```yaml
+numpy:
+  - 1.26  # or similar
+```
+to your `recipe/conda_build_config.yaml`, and then rerender.