docs(release): cite PR #68 in 0.12.0 shipped-via

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: lesnik512

planning/releases/0.12.0.md

@@ -56,5 +56,5 @@ when no decoder claims the model type; `DecodeError` wraps a failure inside
 
 ## Shipped via
 
-PR adding per-verb `*_with_response` siblings to `AsyncClient` and `Client`
+PR #68 — per-verb `*_with_response` siblings on `AsyncClient` and `Client`
 (`src/httpware/client.py`).