Remove deprecated alias of test decorators (2/2)

The attr decorator was deprecated during Pike cycle[1] and multiple
cycles have passed since then.

[1] 3b46d27c90aa6289724f4c137a0838c89d116b62

Depends-on: https://review.opendev.org/908551
Change-Id: Ib24acdd68d1639cd0353f40db1bc9a32b3cecae8
diff --git a/releasenotes/notes/cleanup-attr-decorator-alias-78ce21eb20d87e01.yaml b/releasenotes/notes/cleanup-attr-decorator-alias-78ce21eb20d87e01.yaml
new file mode 100644
index 0000000..43091e1
--- /dev/null
+++ b/releasenotes/notes/cleanup-attr-decorator-alias-78ce21eb20d87e01.yaml
@@ -0,0 +1,5 @@
+---
+upgrade:
+  - |
+    The ``attr`` decorator is no longer available in the ``tempest.test``
+    module. Use the ``tempest.lib.decorators`` module instead.